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-v2014.07.rst b/doc/develop/statistics/u-boot-stats-v2014.07.rst
index d931ca0..d3b47f6 100644
--- a/doc/develop/statistics/u-boot-stats-v2014.07.rst
+++ b/doc/develop/statistics/u-boot-stats-v2014.07.rst
@@ -3,7 +3,7 @@
 Release Statistics for U-Boot v2014.07
 ======================================
 
-* Processed 1074 csets from 146 developers
+* Processed 1074 changesets from 146 developers
 
 * 30 employers found