Update YAMLSyntax.rst with yamllint (#66622)

* Update YAMLSyntax.rst with yamllint

Co-authored-by: Sandra McCann <samccann@redhat.com>

docs/docsite/rst/reference_appendices/YAMLSyntax.rst

@@ -40,21 +40,21 @@ A dictionary is represented in a simple ``key: value`` form (the colon must be f
 
     # An employee record
     martin:
-        name: Martin D'vloper
-        job: Developer
-        skill: Elite
+      name: Martin D'vloper
+      job: Developer
+      skill: Elite
 
 More complicated data structures are possible, such as lists of dictionaries, dictionaries whose values are lists or a mix of both::
 
     # Employee records
-    -  martin:
+    - martin:
         name: Martin D'vloper
         job: Developer
         skills:
           - python
           - perl
           - pascal
-    -  tabitha:
+    - tabitha:
         name: Tabitha Bitumen
         job: Developer
         skills:
@@ -80,6 +80,8 @@ Ansible doesn't really use these too much, but you can also specify a boolean va
     likes_emacs: TRUE
     uses_cvs: false
 
+Use lowercase 'true' or 'false' for boolean values in dictionaries if you want to be compatible with default yamllint options.
+
 Values can span multiple lines using ``|`` or ``>``.  Spanning multiple lines using a "Literal Block Scalar" ``|`` will include the newlines and any trailing spaces.
 Using a "Folded Block Scalar" ``>`` will fold newlines to spaces; it's used to make what would otherwise be a very long line easier to read and edit.
 In either case the indentation will be ignored.
@@ -117,18 +119,18 @@ This really has nothing to do with Ansible, but will give you a feel for the for
     skill: Elite
     employed: True
     foods:
-        - Apple
-        - Orange
-        - Strawberry
-        - Mango
+      - Apple
+      - Orange
+      - Strawberry
+      - Mango
     languages:
-        perl: Elite
-        python: Elite
-        pascal: Lame
+      perl: Elite
+      python: Elite
+      pascal: Lame
     education: |
-        4 GCSEs
-        3 A-Levels
-        BSc in the Internet of Things
+      4 GCSEs
+      3 A-Levels
+      BSc in the Internet of Things
 
 That's all you really need to know about YAML to start writing `Ansible` playbooks.
 
@@ -238,4 +240,3 @@ value::
        implementing
    `YAML 1.2 Specification <https://yaml.org/spec/1.2/spec.html>`_
        For completeness, YAML 1.2 is the successor of 1.1
-