LLM Policy for Rust Compiler

Add an LLM policy for rust-lang/rust #1040 Conversation FCP link Summary This document establishes a policy for how LLMs can be used when contributing to rust-lang/rust . Subtrees, submodules, and dependencies from crates.io are not in scope. Other repositories in the rust-lang organization are not in scope. This policy is intended to live in Forge as a living document, not as a dead RFC. It will ...