Docs: Expanded how to use filters in GraphQL Reference (#11017)
Docs: Expanded how to use filters in GraphQL Reference (#11017)

Summary: The GraphQL Reference will now contain information about all the
 available filter operators, with examples of how to use them.
A link to the test file /packages/gatsby/src/schema/__tests__/run-query.j
s has been added for reference.

Closes https://github.com/gatsbyjs/gatsby/issues/10908
gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby