Rename GraphQL nav item to match page title

What does this MR do and why?

In Rename GraphQL reference page title (gitlab!126478 - merged) I was attempting to make the nav item and page title for the GraphQL API resources page match. It was suggested to go with GraphQL API resources in both places, so this is the change to the left hand nav item.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Check the left hand navigation to make sure the GraphQL API resources page is correctly titled

Merge request acceptance checklist

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• I have evaluated the MR acceptance checklist for this merge request.