Add tentative "community-maintained" disclaimer
Add tentative "community-maintained" disclaimer

[@lervag](https://github.com/lervag), please feel free to update this at
your discretion. The main point I wanted to make is that I am happy to
commit to maintaining this page and am the person to contact in the
event of mistakes/changes.

lervag/vimtex,lervag/vimtex