Merge branch 'adds-basic-terraform-ci-tempalte-latest-docs' into 'master'

Adds Terraform quick start guide

See merge request gitlab-org/gitlab!45057

doc/user/infrastructure/index.md

@@ -13,6 +13,32 @@ workflows to tie into GitLab's authentication and authorization. These features
 lowering the barrier to entry for teams to adopt Terraform, collaborate effectively within
 GitLab, and support Terraform best practices.
 
+## Quick Start
+
+Use the following `.gitlab-ci.yml` to set up a simple Terraform project integration
+for GitLab versions 13.5 and greater:
+
+```yaml
+include:
+  - template: Terraform.latest.gitlab-ci.yml
+
+variables:
+  # If not using GitLab's HTTP backend, remove this line and specify TF_HTTP_* variables
+  TF_STATE_NAME: default
+  TF_CACHE_KEY: default
+```
+
+This template uses `.latest.`, instead of stable, and may include breaking changes.
+This template also includes some opinionated decisions, which you can override:
+
+- Including the latest [GitLab Terraform Image](https://gitlab.com/gitlab-org/terraform-images).
+- Using the [GitLab managed Terraform State](#gitlab-managed-terraform-state) as
+  the Terraform state storage backend.
+- Creating [four pipeline stages](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Terraform.latest.gitlab-ci.yml):
+  `init`, `validate`, `build`, and `deploy`. These stages
+  [run the Terraform commands](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Terraform/Base.latest.gitlab-ci.yml)
+  `init`, `validate`, `plan`, `plan-json`, and `apply`. The `apply` command only runs on `master`.
+
 ## GitLab managed Terraform State
 
 > [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/2673) in GitLab 13.0.
@@ -295,15 +321,15 @@ rerun this command to reinitialize your working directory. If you forget, other
 commands will detect it and remind you to do so if necessary.
 ```
 
-If you type `yes`, it will copy your state from the old location to the new
+If you type `yes`, it copies your state from the old location to the new
 location. You can then go back to running it from within GitLab CI.
 
 ## Output Terraform Plan information into a merge request
 
 Using the [GitLab Terraform Report artifact](../../ci/pipelines/job_artifacts.md#artifactsreportsterraform),
 you can expose details from `terraform plan` runs directly into a merge request widget,
-enabling you to see statistics about the resources that Terraform will create,
-modify, or destroy.
+enabling you to see statistics about the resources that Terraform creates,
+modifies, or destroys.
 
 Let's explore how to configure a GitLab Terraform Report artifact. You can
 either use a pre-built image which includes a `gitlab-terraform` helper as
@@ -435,7 +461,8 @@ apply:
 
 ### Multiple Terraform Plan reports
 
-Starting with 13.2, you can display multiple reports on the Merge Request page. The reports will also display the `artifacts: name:`. See example below for a suggested setup.
+Starting with GitLab version 13.2, you can display multiple reports on the Merge Request
+page. The reports also display the `artifacts: name:`. See example below for a suggested setup.
 
 ```yaml
 default: