[gimp] HACKING: add a comment about the 3 config files for common editors.

[Jehan Pagès <jehanp src gnome org>]

commit acfca30899e4831a689282911e0ced00dc5f4aad
Author: Jehan <jehan girinstud io>
Date:   Tue Aug 23 19:58:22 2016 +0200

    HACKING: add a comment about the 3 config files for common editors.
    
    We have coding style config files for Emacs, Kate and Vim.

 HACKING |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/HACKING b/HACKING
index 316547b..7d3fdc7 100644
--- a/HACKING
+++ b/HACKING
@@ -151,6 +151,12 @@ style is enforced.  The GIMP coding style is defined as follows:
           starting in the first column of the following line. All
           parameters are prototyped and there's a new line for each.
 
+The source tree contains local config files which can be used to set the
+right coding style in common editors: `.dir-locals.el` for Emacs,
+`.kateconfig` for Kate, and `devel-docs/c.vim` for Vim (check the top
+comments to see how to enable it automatically when opening a file in
+the GIMP tree).
+
 Try to make use of GLib's object system as much as possible. Do not
 create wrappers around functions of parent classes. If you end up
 duplicating code, try to create a common parent class and implement