libgit2 required for macOS Silicon

[marcus-crane]

Hey there,

Congrats on the HN traffic over the weekend 🙂

I was just about to experiment with the tool and received the following error:

dyld[19594]: Library not loaded: /opt/homebrew/opt/libgit2/lib/libgit2.1.9.dylib
  Referenced from: <FA8982F5-6820-3A54-B946-90D0836DBF39> /usr/local/bin/git-remote-sqlite
  Reason: tried: '/opt/homebrew/opt/libgit2/lib/libgit2.1.9.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/opt/homebrew/opt/libgit2/lib/libgit2.1.9.dylib' (no such file), '/opt/homebrew/opt/libgit2/lib/libgit2.1.9.dylib' (no such file)
[1]    19594 abort      git-remote-sqlite

The fix was installing libgit2 via Homebrew but would be good to mention in the docs