Add proper lexers to all code blocks in the docs

Thanks for the suggestions. Since tests are passing, and this work can be separated out as an independent task, let's revisit this when I am more familiar with what these elements are you want applied and put all the code block changes in separate PR at a later time.

_Originally posted by @tvo318 in https://github.com/ansible/awx-plugins/pull/100#discussion_r1991936996_