Merge pull request #3945 from radekmie/patch-1

Fixed typo in GraphQL API docs (fixes #3943).

Author: janiceilene

content/graphql/guides/using-the-graphql-api-for-discussions.md

@@ -83,7 +83,7 @@ discussionCategories(
 
 ### Repository.discussion
 
-Get a discussion. Returns `null` if discussion with the specified ID exists.
+Get a discussion. Returns `null` if discussion with the specified ID does not exist.
 
 _Signature:_