gitignore: fix wording

Git files are the files that we don't want to ignore even if
they are dot-files. It must be "even if" but it says "even it".

Signed-off-by: Kyeongmin Cho <korea.drzix@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

.gitignore

@@ -62,7 +62,7 @@ Module.symvers
 /tar-install/
 
 #
-# git files that we don't want to ignore even it they are dot-files
+# git files that we don't want to ignore even if they are dot-files
 #
 !.gitignore
 !.mailmap