fix link to PR

Author: nikomatsakis

text/2795-format-args-implicit-identifiers.md

@@ -1,6 +1,6 @@
 - Feature Name: `format_args_implicits`
 - Start Date: 2019-10-27
-- RFC PR: [rust-lang/rfcs#0000](https://github.com/rust-lang/rfcs/pull/0000)
+- RFC PR: [rust-lang/rfcs#2795](https://github.com/rust-lang/rfcs/pull/2795)
 - Rust Issue: [rust-lang/rust#67984](https://github.com/rust-lang/rust/issues/67984)