[banshee] README.releasing: hint about how to gather contributors for a release

[Andrés Aragoneses <aaragoneses src gnome org>]

commit 8a106618346aaccff5e64d274fd0e46b4c5db153
Author: Andrés G. Aragoneses <knocte gmail com>
Date:   Tue Mar 18 12:50:50 2014 +0100

    README.releasing: hint about how to gather contributors for a release
    
    Original script grabbed from smuxi repo:
    https://github.com/meebey/smuxi/blob/0.10/build/git-contributors

 extras/README.releasing |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/extras/README.releasing b/extras/README.releasing
index d513d30..6dfcec5 100644
--- a/extras/README.releasing
+++ b/extras/README.releasing
@@ -3,7 +3,11 @@ To make a release:
 Pre-release:
 * If it's a stable release, check this first:
 https://wiki.gnome.org/Apps/Banshee/StableReleasesPolicy
-* Update src/Core/Banshee.Core/Resources/contributors.xml (manually)
+* Update src/Core/Banshee.Core/Resources/contributors.xml
+  + This needs to be done manually, but there's a handy command
+    that can help you a lot:
+  `git log 2.9.0..HEAD --no-merges "$@" | grep ^Author: | sed 's/ <.*//; s/^Author: //' | sort | uniq -c | 
sort -nr`
+  (if the previous release was 2.9.0)
 * Update AUTHORS (cd extras/ && ./create-authors > ../AUTHORS)
 * Update NEWS
 * Check version in configure.ac (don't forget the display version)