Link plan in the README

Author: arora-aman

README.md

@@ -6,5 +6,6 @@ See also:
 
 * [RFC 2229]
 * [Rust tracking issue, rust-lang/rust#53488](https://github.com/rust-lang/rust/issues/53488)
+* [Plan](https://hackmd.io/HNEgTkPlTuy6cb9v29rzIQ)
 
 [RFC 2229]: https://github.com/rust-lang/rfcs/blob/master/text/2229-capture-disjoint-fields.md