Bug - Update broken and inaccurate links across patternfly.org.

[edonehoo]

I've noticed a handful of links that can be updated across the website--both for v5 and v6. Some of these are broken and some could just be more helpful.

To name a few (but I'll look around for more with a broken link checker tool):
v5

• Footer quicklinks: these can point to the "about" landing pages instead
• Broken
  • Date picker design guidelines
  • Alert design guidelines

v6

• Footer quicklinks: these can point to the "about" landing pages instead
• any links to contribute or community pages
• Broken
  • Date picker design guidelines
  • Alert design guidelines