Identify & resolve any custom styles

[kmcfaul]

We should be able to remove all the CSS copied from core's pf-v6-c-content: https://github.com/patternfly/patternfly-org/blob/v6/packages/documentation-framework/templates/mdx.css#L90.

Looks like we can remove custom styles for the sidebar nav, which should resolve this issue #3953

[mcoker]

Once patternfly/patternfly#5966 is complete, assuming those styles are pretty much a copy of the core pf-[v]-c-content (aka, react <Text> and <TextContent>) component, ideally, we should be able to yank out those styles and swap .ws-[p/dl/hr/etc] with classes from the content/text/textcontent component - eg, .pf-v6-c-content--[p/dl/hr/etc].