documentation: whitespace is already generally plural

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Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

Documentation/config/apply.txt

@@ -7,5 +7,5 @@ apply.ignoreWhitespace::
 	See linkgit:git-apply[1].
 
 apply.whitespace::
-	Tells 'git apply' how to handle whitespaces, in the same way
+	Tells 'git apply' how to handle whitespace, in the same way
 	as the `--whitespace` option. See linkgit:git-apply[1].