git:ignore: Add /.git

Ignore the .git directory globally instead of ignoring it manually in
tools like fd and ripgrep.

I feel very dumb for putting all this time into the redefinition of :Rg,
especially since I am currently **much** procrastinating writing my
bachelor thesis.

.config/git/ignore

@@ -1,3 +1,6 @@
+# Ignore .git directory (mostly for tools like rg and fd)
+/.git
+
 # Ignore all compiled zsh-files
 *.zwc