doc: fix singular/plural mismatch in git-rerere

conflict -> conflicts

Signed-off-by: Elijah Newren <newren@gmail.com>

Author: newren

Documentation/git-rerere.adoc

@@ -44,7 +44,7 @@ will automatically invoke this command.
 'forget' <pathspec>::
 
 Reset the conflict resolutions which rerere has recorded for the current
-conflict in paths that match <pathspec>.
+conflicts in paths that match <pathspec>.
 
 'diff'::