Test rstcheck version 6

[samccann]

Currently we can't update our docs dependencies to rstcheck 6.0 or above because it spits out too many warnings in CI tests to fix before the 2.14 branch pull.

We need to :

• update to 6 (see https://github.com/ansible/ansible/pull/78674/files# for examples of what might need to change)
• update test/sanity/code-smell/rstcheck.py to work with the restructured code. Specifically:
  

[samccann]

related to ansible/ansible#78478

[samccann]

closing in favor of above issue.