Update boards doc for GraphQL board gitlab.com rollout
What does this MR do?
This documentation update should accompany the rollout of ':graphql_board_lists' feature flag for gitlab.com.
Does this MR meet the acceptance criteria?
Conformity
- [-] I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
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I have added/updated documentation, or it's not needed. (Is documentation required?) -
I have self-reviewed this MR per code review guidelines.
Edited by euko