Merge branch 'docs-ssot-api-templates' into 'master'

SSoT for API template docs

Closes #64589

See merge request gitlab-org/gitlab-ce!31320

doc/api/templates/dockerfiles.md

+---
+type: reference
+---
+
 # Dockerfiles API
 
+In GitLab, there is an API endpoint available for Dockerfiles. For more
+information on Dockerfiles, see the
+[Docker documentation](https://docs.docker.com/engine/reference/builder/).
+
 ## List Dockerfile templates
 
 Get all Dockerfile templates.
@@ -111,3 +119,15 @@ Example response:
   "content": "# This file is a template, and might need editing before it works on your project.\n# This Dockerfile installs a compiled binary into a bare system.\n# You must either commit your compiled binary into source control (not recommended)\n# or build the binary first as part of a CI/CD pipeline.\n\nFROM buildpack-deps:jessie\n\nWORKDIR /usr/local/bin\n\n# Change `app` to whatever your binary is called\nAdd app .\nCMD [\"./app\"]\n"
 }
 ```
+
+<!-- ## Troubleshooting
+
+Include any troubleshooting steps that you can foresee. If you know beforehand what issues
+one might have when setting this up, or when something is changed, or on upgrading, it's
+important to describe those, too. Think of things that may go wrong and include them here.
+This is important to minimize requests for support, and to avoid doc comments with
+questions that you know someone might ask.
+
+Each scenario can be a third-level heading, e.g. `### Getting error message X`.
+If you have none to add when creating a doc, leave this section in place
+but commented out to help encourage others to add to it in the future. -->

doc/api/templates/gitignores.md

-# `.gitignore` API
+---
+type: reference
+---
+
+# .gitignore API
+
+In GitLab, there is an API endpoint available for `.gitignore`. For more
+information on `gitignore`, see the
+[Git documentation](https://git-scm.com/docs/gitignore).
 
 ## List `.gitignore` templates
 
@@ -123,3 +131,15 @@ Example response:
   "content": "*.gem\n*.rbc\n/.config\n/coverage/\n/InstalledFiles\n/pkg/\n/spec/reports/\n/spec/examples.txt\n/test/tmp/\n/test/version_tmp/\n/tmp/\n\n# Used by dotenv library to load environment variables.\n# .env\n\n## Specific to RubyMotion:\n.dat*\n.repl_history\nbuild/\n*.bridgesupport\nbuild-iPhoneOS/\nbuild-iPhoneSimulator/\n\n## Specific to RubyMotion (use of CocoaPods):\n#\n# We recommend against adding the Pods directory to your .gitignore. However\n# you should judge for yourself, the pros and cons are mentioned at:\n# https://guides.cocoapods.org/using/using-cocoapods.html#should-i-check-the-pods-directory-into-source-control\n#\n# vendor/Pods/\n\n## Documentation cache and generated files:\n/.yardoc/\n/_yardoc/\n/doc/\n/rdoc/\n\n## Environment normalization:\n/.bundle/\n/vendor/bundle\n/lib/bundler/man/\n\n# for a library or gem, you might want to ignore these files since the code is\n# intended to run in multiple environments; otherwise, check them in:\n# Gemfile.lock\n# .ruby-version\n# .ruby-gemset\n\n# unless supporting rvm < 1.11.0 or doing something fancy, ignore this:\n.rvmrc\n"
 }
 ```
+
+<!-- ## Troubleshooting
+
+Include any troubleshooting steps that you can foresee. If you know beforehand what issues
+one might have when setting this up, or when something is changed, or on upgrading, it's
+important to describe those, too. Think of things that may go wrong and include them here.
+This is important to minimize requests for support, and to avoid doc comments with
+questions that you know someone might ask.
+
+Each scenario can be a third-level heading, e.g. `### Getting error message X`.
+If you have none to add when creating a doc, leave this section in place
+but commented out to help encourage others to add to it in the future. -->

doc/api/templates/gitlab_ci_ymls.md

+---
+type: reference
+---
+
 # GitLab CI YMLs API
 
+In GitLab, there is an API endpoint available to work with CI YMLs. For more
+information on CI/CD pipeline configuration in GitLab, see the
+[configuration reference documentation](../../ci/yaml/README.md).
+
 ## List GitLab CI YML templates
 
 Get all GitLab CI YML templates.
@@ -123,3 +131,15 @@ Example response:
   "content": "# This file is a template, and might need editing before it works on your project.\n# Official language image. Look for the different tagged releases at:\n# https://hub.docker.com/r/library/ruby/tags/\nimage: \"ruby:2.5\"\n\n# Pick zero or more services to be used on all builds.\n# Only needed when using a docker container to run your tests in.\n# Check out: http://docs.gitlab.com/ce/ci/docker/using_docker_images.html#what-is-a-service\nservices:\n  - mysql:latest\n  - redis:latest\n  - postgres:latest\n\nvariables:\n  POSTGRES_DB: database_name\n\n# Cache gems in between builds\ncache:\n  paths:\n    - vendor/ruby\n\n# This is a basic example for a gem or script which doesn't use\n# services such as redis or postgres\nbefore_script:\n  - ruby -v                                   # Print out ruby version for debugging\n  # Uncomment next line if your rails app needs a JS runtime:\n  # - apt-get update -q && apt-get install nodejs -yqq\n  - bundle install -j $(nproc) --path vendor  # Install dependencies into ./vendor/ruby\n\n# Optional - Delete if not using `rubocop`\nrubocop:\n  script:\n  - rubocop\n\nrspec:\n  script:\n  - rspec spec\n\nrails:\n  variables:\n    DATABASE_URL: \"postgresql://postgres:postgres@postgres:5432/$POSTGRES_DB\"\n  script:\n  - rails db:migrate\n  - rails db:seed\n  - rails test\n\n# This deploy job uses a simple deploy flow to Heroku, other providers, e.g. AWS Elastic Beanstalk\n# are supported too: https://github.com/travis-ci/dpl\ndeploy:\n  type: deploy\n  environment: production\n  script:\n  - gem install dpl\n  - dpl --provider=heroku --app=$HEROKU_APP_NAME --api-key=$HEROKU_PRODUCTION_KEY\n"
 }
 ```
+
+<!-- ## Troubleshooting
+
+Include any troubleshooting steps that you can foresee. If you know beforehand what issues
+one might have when setting this up, or when something is changed, or on upgrading, it's
+important to describe those, too. Think of things that may go wrong and include them here.
+This is important to minimize requests for support, and to avoid doc comments with
+questions that you know someone might ask.
+
+Each scenario can be a third-level heading, e.g. `### Getting error message X`.
+If you have none to add when creating a doc, leave this section in place
+but commented out to help encourage others to add to it in the future. -->

doc/api/templates/licenses.md

+---
+type: reference
+---
+
 # Licenses API
 
+In GitLab, there is an API endpoint available for working with various open
+source license templates. For more information on the terms of various
+licenses, see [this site](https://choosealicense.com/) or any of the many other
+resources available online.
+
 ## List license templates
 
 Get all license templates.
@@ -145,3 +154,15 @@ Example response:
     "content": "The MIT License (MIT)\n\nCopyright (c) 2016 John Doe\n [...]"
 }
 ```
+
+<!-- ## Troubleshooting
+
+Include any troubleshooting steps that you can foresee. If you know beforehand what issues
+one might have when setting this up, or when something is changed, or on upgrading, it's
+important to describe those, too. Think of things that may go wrong and include them here.
+This is important to minimize requests for support, and to avoid doc comments with
+questions that you know someone might ask.
+
+Each scenario can be a third-level heading, e.g. `### Getting error message X`.
+If you have none to add when creating a doc, leave this section in place
+but commented out to help encourage others to add to it in the future. -->