Add lua.cr and luajit.cr to Misc section

[hahwul]

Link

• https://github.com/veelenga/lua.cr
• https://github.com/mdwagner/luajit.cr

Checklist

• - Shard is at least 30 days old.
• - Shard has CI implemented.
• - Shard has daily/weekly periodic builds (ideally with Crystal latest and nightly).

For luajit.cr, only Pre-release versions are available, so the last checklist item is a bit ambiguous. If it doesn't meet the criteria, please close this PR! If closed, I'll submit lua.cr separately.

[veelenga]

Thanks for the pull request. I need to add periodical builds to lua.cr first.

[veelenga]

lgtm