Fix code-blocks to use correct syntax highlighting

docs/docsite/rst/dev_guide/developing_modules.rst

@@ -543,7 +543,7 @@ If you are using Ansible with the :envvar:`ANSIBLE_KEEP_REMOTE_FILES`
 environment variables to keep the remote module file, here's a sample of how
 your debugging session will start:
 
-.. code-block:: sh
+.. code-block:: shell-session
 
     $ ANSIBLE_KEEP_REMOTE_FILES=1 ansible localhost -m ping -a 'data=debugging_session' -vvv
     <127.0.0.1> ESTABLISH LOCAL CONNECTION FOR USER: badger

docs/docsite/rst/dev_guide/developing_test_pr.rst

@@ -180,9 +180,11 @@ If the PR does not resolve the issue, or if you see any failures from the unit/i
    |
    | When I ran this Ubuntu 16.04 it failed with the following:
    |
+   |   ```
    |   BLARG
    |   StrackTrace
    |   RRRARRGGG
+   |   ```
 
 When you are done testing a feature branch, you can remove it with the following command:
 

docs/docsite/rst/playbooks_filters.rst

@@ -453,6 +453,8 @@ It is also possible to fully customize the comment style::
 
 That will create the following output:
 
+.. code-block:: sh
+
 .. code-block:: sh
 
     #######