Simplify template for FCP-complete merging steps

I have to manually copy this from an old merged RFC every time; this change saves me some time.

Author: Centril

0000-template.md

@@ -1,7 +1,7 @@
-- Feature Name: (fill me in with a unique ident, my_awesome_feature)
+- Feature Name: (fill me in with a unique ident, `my_awesome_feature`)
 - Start Date: (fill me in with today's date, YYYY-MM-DD)
-- RFC PR: (leave this empty)
-- Rust Issue: (leave this empty)
+- RFC PR: [rust-lang/rfcs#0000](https://github.com/rust-lang/rfcs/pull/0000)
+- Rust Issue: [rust-lang/rust#0000](https://github.com/rust-lang/rust/issues/0000)
 
 # Summary
 [summary]: #summary