Fix spelling of overridden in documentation

Signed-off-by: Shawn Bohrer <shawn.bohrer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-merge.txt

@@ -56,7 +56,7 @@ merge.verbosity::
 	message if conflicts were detected. Level 1 outputs only
 	conflicts, 2 outputs conflicts and file changes.  Level 5 and
 	above outputs debugging information.  The default is level 2.
-	Can be overriden by 'GIT_MERGE_VERBOSITY' environment variable.
+	Can be overridden by 'GIT_MERGE_VERBOSITY' environment variable.
 
 
 HOW MERGE WORKS

Documentation/gitignore.txt

@@ -26,7 +26,7 @@ precedence, the last matching pattern decides the outcome):
 
  * Patterns read from a `.gitignore` file in the same directory
    as the path, or in any parent directory, with patterns in the
-   higher level files (up to the root) being overriden by those in
+   higher level files (up to the root) being overridden by those in
    lower level files down to the directory containing the file.
    These patterns match relative to the location of the
    `.gitignore` file.  A project normally includes such