Added tests for `taggable` module

Fixes #11521

Fixes #11514

implement jinja2 header overrides

syslog_json call plugin improvements

Fixes #11317

Don't wrap text for AnsibleParserError

This allows not messing up the wonderful error reporting that is
carefully created. Instead of:

    $ ansible-playbook foo.yml
     [ERROR]: ERROR! 'foo' is not a valid attribute for a Task  The error appears
    to have been in '/Users/marca/dev/git-repos/ansible/foo.yml': line 4, column 7,
    but may be elsewhere in the file depending on the exact syntax problem.  The
    offending line appears to be:    tasks:     - name: do something       ^ here

we get:

    $ ansible-playbook foo.yml
    ERROR! 'foo' is not a valid attribute for a Task

    The error appears to have been in '/Users/marca/dev/git-repos/ansible/foo.yml': line 4, column 7, but may
    be elsewhere in the file depending on the exact syntax problem.

    The offending line appears to be:

      tasks:
        - name: do something
          ^ here

which is much nicer.

Update index.rst

Update intro_inventory.rst

fixes #11505

Minor fix for consistency (and more engaging language :))

* Update log message format

Be more specific describing groups of groups,