RFC 1618 is ergonomic format_args!

Author: alexcrichton

text/0000-ergonomic-format-args.md renamed to text/1618-ergonomic-format-args.md

@@ -1,7 +1,7 @@
 - Feature Name: (not applicable)
 - Start Date: 2016-05-17
-- RFC PR: (leave this empty)
-- Rust Issue: (leave this empty)
+- RFC PR: [rust-lang/rfcs#1618](https://github.com/rust-lang/rfcs/pull/1618)
+- Rust Issue: [rust-lang/rust#33642](https://github.com/rust-lang/rust/pull/33642)
 
 # Summary
 [summary]: #summary