ripgrep: Ignore markdown files

When searching in projects like SIPjs, we get a lot of results which are
in markdown files as the documentation in SIPjs is in markdown. We mostly
care about code when searching. So ignore markdown files while searching
just like we ignore a few others.

ripgrep/.config/ripgrep/ripgreprc

@@ -11,3 +11,4 @@
 --glob=!mediasoup/*
 --glob=!mediasoup-*/
 --glob=!north-star/
+--glob=!*.md