Remove excessive typo from docs

Author: nguyenfamj

docs/rtk-query/api/createApi.mdx

@@ -508,7 +508,7 @@ See also [Invalidating cache data](../usage/automated-refetching.mdx#invalidatin
 
 _(optional, only for query endpoints)_
 
-Overrides the api-wide definition of `keepUnusedDataFor` for this endpoint only.a
+Overrides the api-wide definition of `keepUnusedDataFor` for this endpoint only.
 
 [summary](docblock://query/createApi.ts?token=CreateApiOptions.keepUnusedDataFor)