Update some examples to use proper YAML syntax. (#35640)

* Update some examples to use proper YAML syntax.

* Make the requested changes so this builds properly.

Also fix emphasis line numbers to match what was being emphasized before
the change.

docs/docsite/rst/playbooks_blocks.rst

@@ -8,19 +8,26 @@ Blocks allow for logical grouping of tasks and in play error handling. Most of w
  :emphasize-lines: 3
  :caption: Block example
 
-    tasks:
-      - name: Install Apache
-        block:
-          - yum: name={{ item }} state=installed
-            loop:
-              - httpd
-              - memcached
-          - template: src=templates/src.j2 dest=/etc/foo.conf
-          - service: name=bar state=started enabled=True
-        when: ansible_distribution == 'CentOS'
-        become: true
-        become_user: root
 
+  tasks:
+    - name: Install Apache
+      block:
+        - yum:
+            name: "{{ item }}"
+            state: installed
+          with_items:
+            - httpd
+            - memcached
+        - template:
+            src: templates/src.j2
+            dest: /etc/foo.conf
+        - service:
+            name: bar
+            state: started
+            enabled: True
+      when: ansible_distribution == 'CentOS'
+      become: true
+      become_user: root
 
 In the example above, each of the 3 tasks will be executed after appending the `when` condition from the block
 and evaluating it in the task's context. Also they inherit the privilege escalation directives enabling "become to root"
@@ -38,22 +45,27 @@ Error Handling
 Blocks also introduce the ability to handle errors in a way similar to exceptions in most programming languages.
 
 .. code-block:: YAML
- :emphasize-lines: 3,7,11
+ :emphasize-lines: 3,9,15
  :caption: Block error handling example
 
-   tasks:
-    - name: Attempt and gracefull roll back demo
-      block:
-        - debug: msg='I execute normally'
-        - command: /bin/false
-        - debug: msg='I never execute, due to the above task failing'
-      rescue:
-        - debug: msg='I caught an error'
-        - command: /bin/false
-        - debug: msg='I also never execute :-('
-      always:
-        - debug: msg="this always executes"
 
+  tasks:
+  - name: Attempt and gracefull roll back demo
+    block:
+      - debug:
+          msg: 'I execute normally'
+      - command: /bin/false
+      - debug:
+          msg: 'I never execute, due to the above task failing'
+    rescue:
+      - debug:
+          msg: 'I caught an error'
+      - command: /bin/false
+      - debug:
+          msg: 'I also never execute :-('
+    always:
+      - debug:
+          msg: "this always executes"
 
 The tasks in the ``block`` would execute normally, if there is any error the ``rescue`` section would get executed
 with whatever you need to do to recover from the previous error. The ``always`` section runs no matter what previous
@@ -64,21 +76,24 @@ error did or did not occur in the ``block`` and ``rescue`` sections. It should b
 Another example is how to run handlers after an error occurred :
 
 .. code-block:: YAML
- :emphasize-lines: 5,9
+ :emphasize-lines: 6,10
  :caption: Block run handlers in error handling
 
+
   tasks:
     - name: Attempt and gracefull roll back demo
       block:
-        - debug: msg='I execute normally'
+        - debug:
+            msg: 'I execute normally'
           notify: run me even after an error
         - command: /bin/false
       rescue:
         - name: make sure all handlers run
           meta: flush_handlers
-   handlers:
+  handlers:
      - name: run me even after an error
-       debug: msg='this handler runs even on error'
+       debug:
+         msg: 'this handler runs even on error'
 
 .. seealso::