fix: Update RFC number

Author: epage

text/0000-remove-implicit-features.md renamed to text/3491-remove-implicit-features.md

@@ -1,6 +1,6 @@
 - Feature Name: `remove-implicit-feature`
 - Start Date: 2023-09-18
-- RFC PR: [rust-lang/rfcs#0000](https://github.com/rust-lang/rfcs/pull/0000)
+- RFC PR: [rust-lang/rfcs#3491](https://github.com/rust-lang/rfcs/pull/3491)
 - Rust Issue: [rust-lang/rust#0000](https://github.com/rust-lang/rust/issues/0000)
 
 # Summary