[gimp-help] quickreference: mention pot file updating in README

[Jacob Boerema <jboerema src gnome org>]

commit f0431953c9e20b79e65d94892e01371ca0dfce67
Author: Anders Jonsson <anders jonsson norsjovallen se>
Date:   Sat Feb 12 21:10:23 2022 +0100

    quickreference: mention pot file updating in README

 quickreference/README | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/quickreference/README b/quickreference/README
index fa8214e24..154fc3029 100644
--- a/quickreference/README
+++ b/quickreference/README
@@ -17,6 +17,13 @@ use make:
 The files can be found in either 'svg' or 'docbook' directories
 (whatever you created).
 
+The pot file 'po/gimp-keys.pot' is needed in the repository
+for l10n.gnome.org to extract translations from the quickreference.
+Remember to also update and commit that file if you make changes to
+'gimp-keys.xml'.
+
+You will be required to delete the pot file before running 'make pot'
+to create an updated pot file.
 
 Update PO files if the POT has changed
 ======================================