Fix link text for cargo in #3231

Author: ehuss

text/3231-cargo-asymmetric-tokens.md

@@ -1,7 +1,7 @@
 - Feature Name: cargo_asymmetric_tokens
 - Start Date: 2022-02-02
 - RFC PR: [rust-lang/rfcs#3231](https://github.com/rust-lang/rfcs/pull/3231)
-- Cargo Issue: [rust-lang/rust#10519](https://github.com/rust-lang/cargo/issues/10519)
+- Cargo Issue: [rust-lang/cargo#10519](https://github.com/rust-lang/cargo/issues/10519)
 
 # Summary
 [summary]: #summary