fix(docs): Un-stubbing "Sourcing from private APIs" link in sidebar (#11061)
fix(docs): Un-stubbing "Sourcing from private APIs" link in sidebar (#11061)

As the [Sourcing from Private APIs](https://www.gatsbyjs.org/docs/sourcing-from-private-apis/) page no longer seems to be a stub, I removed the stub asterisk.
ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby