runtime(git): Add small ftplugin

runtime/ftplugin/git.vim

@@ -0,0 +1,15 @@
+" Vim filetype plugin
+" Language:	generic git output
+" Maintainer:	Tim Pope <vimNOSPAM@tpope.org>
+" Last Change:	2023 Mar 26
+
+" Only do this when not done yet for this buffer
+if (exists("b:did_ftplugin"))
+  finish
+endif
+
+let b:did_ftplugin = 1
+
+setlocal nomodeline
+
+let b:undo_ftplugin = "setl modeline<"