Game jam is over; next meetup is June.
Mention jam on front page; add UTC time.
fennel-lang.org update events page with game jam info

This patch adds the game-jam info to the community events page as well
as updates the date of the next user group.

Add community events page and user group info to fennel-lang.org

Hi there!

This patch adds information about the previously discussed Fennel User Group.
I think we should create a new events page that covers the Fennel Conf, the Fennel
User Group, and the soon-to-be-created Fennel game jam. I have organized my patch
around that idea, but I am happy to do it another way as well.

Update to Fennel 1.1.0
strip .md from relative markdown links

* renamed pandoc filter to something more generic
* added filter to strip the .md from any non-absolute URLs to ".md"
Wups; we don't have security.html yet; wait till submodule bump.
Bump copyright and clarify a few links.
Add security and style pages.
Use the same footer for previous FennelConf years.
Video links for FennelConf 2021
Surprise un-cancellation
Link to the video mirror.
Remove the bit about submitting fennelconf 2021 talks.
Update antifennel to latest version.
Disable strict globals checks for now; come back to this later.
Add a couple more guides to the documentation.
Bump to version 1.0.0
Fennelconf 2021 is online.