[llvm] [Docs] Update Maintainer in Developer Policy (PR #154687)

[Renato Golin via llvm-commits]

rengolin wrote:

Based on the [draft document](https://docs.google.com/document/d/1lgLjMye3d4xJzZumIdDbDzuh2MTvlmmPAQxe99M7HNk/)  and several discussions in the forums and area teams.

https://github.com/llvm/llvm-project/pull/154687