Add yamllint check for RST code listings (#2385)

* Add yamllint check for RST code listings.

* Address review comments.

* Sort languages and remove no longer needed duplicates.

* Enable warnings, but disable all failing rules.

* Improve formulation.

Co-authored-by: Don Naro <dnaro@redhat.com>

* Show allowed languages when no or invalid language is supplied. Improve line lengths.

* Make sure that 'yamllint .' passes.

* Fix indentation issues introduced in #2095.

---------

Co-authored-by: Don Naro <dnaro@redhat.com>

.github/workflows/build-package-docs.yaml

@@ -1,6 +1,6 @@
 ---
 name: Build and deploy docs
-on:
+"on":
   schedule:
     # Run at 05:17 on Tuesday and Thursday
     - cron: '17 5 * * 2,4'

.github/workflows/ci.yaml

@@ -1,8 +1,8 @@
 name: Ansible Docsite CI
 
-on:
+"on":
   schedule:
-    # Daily 
+    # Daily
     - cron: "23 7 * * *"
   push:
     branches-ignore:

.github/workflows/reusable-nox.yml

@@ -25,6 +25,8 @@ jobs:
             python-versions: "3.11"
           - session: "checkers(rstcheck)"
             python-versions: "3.11"
+          - session: "checkers(rst-yamllint)"
+            python-versions: "3.11"
           - session: "checkers(docs-build)"
             python-versions: "3.11"
           - session: "actionlint"