[Docs] update docs to 0.50

[tac0turtle]

Summary

list of docs that need to be updated:

• auto cli replace all query
• [Docs]: core api adoption #17207
• additional fields in context.go to be added to context.md #17034
• Document new GetSigners in UPGRADING.md #16294 (@tac0turtle)
• docs: add docs on proto annotations  #15548
• Explain what Precommiter and PrepareCheckState are and what you can do with it (Audit types v0.47...v0.50 #16475 (comment))

[tac0turtle]

@samricotta are you able to pick up the last bullet point?