merge RFC 2845: Supertrait Item Shadowing.

Author: pnkfelix

text/0000-supertrait-item-shadowing.md renamed to text/2845-supertrait-item-shadowing.md

@@ -1,7 +1,7 @@
 - Feature Name: `supertrait_item_shadowing`
 - Start Date: 2020-01-06
-- 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)
+- RFC PR: [rust-lang/rfcs#2845](https://github.com/rust-lang/rfcs/pull/2845)
+- Rust Issue: [rust-lang/rust#0000](https://github.com/rust-lang/rust/issues/89151)
 
 # Summary
 [summary]: #summary