Fix typo in MAINTAINERS

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

MAINTAINERS

@@ -141,7 +141,7 @@ editor, and thus asking them to `git commit --amend -s` is not the best way forw
 In this case, maintainers can update the commits based on clause (c) of the DCO. The
 most trivial way for a contributor to allow the maintainer to do this, is to add
 a DCO signature in a Pull Requests's comment, or a maintainer can simply note that
-the change is sufficiently trivial that it does not substantivly change the existing
+the change is sufficiently trivial that it does not substantially change the existing
 contribution - i.e., a spelling change.
 
 When you add someone's DCO, please also add your own to keep a log.