Fixup RFC 2349: Pin APIs.

Author: boats

text/0000-pin.md renamed to text/2349-pin.md

@@ -1,7 +1,7 @@
-- Feature Name: pins_and_needles
+- Feature Name: pin
 - Start Date: 2018-02-19
-- RFC PR: (leave this empty)
-- Rust Issue: (leave this empty)
+- RFC PR: https://github.com/rust-lang/rfcs/pull/2349
+- Rust Issue: https://github.com/rust-lang/rust/issues/49150
 
 # Summary
 [summary]: #summary