This PR:
- Adds more redirects: https://github.com/a11yproject/a11yproject.com/issues/1018, https://github.com/a11yproject/a11yproject.com/issues/1000
- Fixes inaccurate IDs
- Adds a known issues subsection to our accessibility statement: https://github.com/a11yproject/a11yproject.com/issues/960
- Updates 1.1.0 announcement notes: https://github.com/a11yproject/a11yproject.com/pull/1006
- Adds a details/summary polyfil: https://github.com/a11yproject/a11yproject.com/issues/941
- Adds a link to our project on GitHub to the footer