docs(ref): Have msrv-policy feature link to RFC

Author: epage

src/doc/src/reference/unstable.md

@@ -331,6 +331,7 @@ Documentation updates:
 - For workspace's "The `dependencies` table" section, include `public` as an unsupported field for `workspace.dependencies`
 
 ## msrv-policy
+- [RFC: MSRV-aware Resolver](https://rust-lang.github.io/rfcs/3537-msrv-resolver.html)
 - [#9930](https://github.com/rust-lang/cargo/issues/9930) (MSRV-aware resolver)
 
 Catch-all unstable feature for MSRV-aware cargo features under