doc: Use "changesets" not "csets" in statistics pages

To make things more human readable, say "changesets from" rather than
"csets from" in all our historical pages here. Moving forward this has
been changed in our gitdm with b034e399e31a ("gitdm: fix typo csets").

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/develop/statistics/u-boot-stats-v2014.01.rst b/doc/develop/statistics/u-boot-stats-v2014.01.rst
index 809f3ff..5842269 100644
--- a/doc/develop/statistics/u-boot-stats-v2014.01.rst
+++ b/doc/develop/statistics/u-boot-stats-v2014.01.rst
@@ -3,7 +3,7 @@
 Release Statistics for U-Boot v2014.01
 ======================================
 
-* Processed 980 csets from 154 developers
+* Processed 980 changesets from 154 developers
 
 * 31 employers found