editorconfig: add .bash extension

Both files in the command below appear to be indented with tabs, and I'd
expect .bash files to have roughly the same style as .sh files.

$ find . -name \*.bash
./contrib/completion/git-completion.bash
./ci/check-directional-formatting.bash

Signed-off-by: David Mandelberg <david@mandelberg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.editorconfig

@@ -4,7 +4,7 @@ insert_final_newline = true
 
 # The settings for C (*.c and *.h) files are mirrored in .clang-format.  Keep
 # them in sync.
-[{*.{c,h,sh,perl,pl,pm,txt,adoc},config.mak.*,Makefile}]
+[{*.{c,h,sh,bash,perl,pl,pm,txt,adoc},config.mak.*,Makefile}]
 indent_style = tab
 tab_width = 8