Merge branch 'bprescott-allowedtofail2-20200206' into 'master'

docs: CI rules: manual does not set 'allowed to fail' automatically

See merge request gitlab-org/gitlab!24589

doc/ci/yaml/README.md

@@ -1264,7 +1264,9 @@ osx job:
 
 `allow_failure` allows a job to fail without impacting the rest of the CI
 suite.
-The default value is `false`, except for [manual](#whenmanual) jobs.
+The default value is `false`, except for [manual](#whenmanual) jobs using the
+`when: manual` syntax, unless using [`rules:`](#rules) syntax, where all jobs
+default to false, *including* `when: manual` jobs.
 
 When enabled and the job fails, the job will show an orange warning in the UI.
 However, the logical flow of the pipeline will consider the job a
@@ -1379,14 +1381,17 @@ manual action by clicking a _play_ button.
 
 When a pipeline is blocked, it will not be merged if Merge When Pipeline Succeeds
 is set. Blocked pipelines also do have a special status, called _manual_.
-Manual actions are non-blocking by default. If you want to make manual action
-blocking, it is necessary to add `allow_failure: false` to the job's definition
-in `.gitlab-ci.yml`.
+When the `when:manual` syntax is used, manual actions are non-blocking by
+default. If you want to make manual action blocking, it is necessary to add
+`allow_failure: false` to the job's definition in `.gitlab-ci.yml`.
 
 Optional manual actions have `allow_failure: true` set by default and their
 Statuses do not contribute to the overall pipeline status. So, if a manual
 action fails, the pipeline will eventually succeed.
 
+NOTE: **Note:**
+When using [`rules:`](#rules), `allow_failure` defaults to `false`, including for manual jobs.
+
 Manual actions are considered to be write actions, so permissions for
 [protected branches](../../user/project/protected_branches.md) are used when
 a user wants to trigger an action. In other words, in order to trigger a manual