[gparted] Add translatable files reminder to HACKING file

[Curtis Gedak <gedakc src gnome org>]

commit 77978ee7c12d8b3a4d783c43e4144da203f4592a
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Fri Oct 14 07:54:55 2016 +0100

    Add translatable files reminder to HACKING file

 HACKING |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/HACKING b/HACKING
index 28d5cb4..738aa13 100644
--- a/HACKING
+++ b/HACKING
@@ -20,6 +20,18 @@ Curtis
 
 
 
+Translatable files
+==================
+
+The file po/POTFILES.in lists all source files which do or could contain
+translatable strings.  Remember to update when adding new and removing
+old source code files include/*.h and src/*.cc.  Generally .cc files are
+included and .h files are not, but there are exceptions.  Some mistakes
+can be detected using:
+    make distcheck
+
+
+
 partition usage and unallocated space
 =====================================