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-v2009.11.rst b/doc/develop/statistics/u-boot-stats-v2009.11.rst
index b9f64b1..2e1b2ea 100644
--- a/doc/develop/statistics/u-boot-stats-v2009.11.rst
+++ b/doc/develop/statistics/u-boot-stats-v2009.11.rst
@@ -3,7 +3,7 @@
 Release Statistics for U-Boot v2009.11
 ======================================
 
-* Processed 531 csets from 90 developers
+* Processed 531 changesets from 90 developers
 
 * 39 employers found