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-v2016.11.rst b/doc/develop/statistics/u-boot-stats-v2016.11.rst
index 3bf61d5..9fb6e3e 100644
--- a/doc/develop/statistics/u-boot-stats-v2016.11.rst
+++ b/doc/develop/statistics/u-boot-stats-v2016.11.rst
@@ -3,7 +3,7 @@
 Release Statistics for U-Boot v2016.11
 ======================================
 
-* Processed 1031 csets from 114 developers
+* Processed 1031 changesets from 114 developers
 
 * 26 employers found