Drop the explicit editor config in .gitconfig

We pretty ironclad specify EDITOR now, don't want
to use vim, and don't trust every box to have hx
on it. We could make this a thing in the git local
but trusting EDITOR is probably best.

.gitconfig

@@ -4,7 +4,6 @@
 [core]
 	# Declare erroenous the same whitespace errors vim does
 	whitespace = space-before-tab,-indent-with-non-tab,trailing-space
-	editor = vim
 
 [diff]
 	# Detect both copies and renames in diffs