editorconfig: Unset maximum line length for .git

An editorconfig's asterix section applies to the whole file tree,
including the .git folder. The Git commit message dialog is a temporary
file named .git/COMMIT_EDITMSG, which the editorconfig applies to.

To avoid having the line length of commit messages changed to 100 chars,
add a rule to specifically unset the max_line_length for the .git
folder.

.editorconfig

@@ -9,6 +9,9 @@ indent_style = tab
 indent_size = 4
 max_line_length = 100
 
+[/.git/**]
+max_line_length = unset
+
 [*.xml]
 indent_style = space
 indent_size = 2