Spelling fix.

admin/notes/years

@@ -3,7 +3,7 @@ HOW TO MAINTAIN COPYRIGHT YEARS FOR GNU EMACS
 Maintaining copyright years is now very simple: every time a new year
 rolls around, add that year to every FSF (and AIST) copyright notice.
 Do this by running the 'admin/update-copyright' script on a fresh bzr
-checkout.  Inspect the results for plausiblity, then commit them.
+checkout.  Inspect the results for plausibility, then commit them.
 
 There's no need to worry about whether an individual file has changed
 in a given year - it's sufficient that Emacs as a whole has changed.