Rollup merge of #103766 - lukas-code:error-in-core, r=Dylan-DPC

Add tracking issue to `error_in_core`

This was merged in rust-lang/rust#99917 without a tracking issue, so I'm creating one now: rust-lang/rust#103765

Author: Dylan-DPC

core/src/error.rs

@@ -1,5 +1,5 @@
 #![doc = include_str!("error.md")]
-#![unstable(feature = "error_in_core", issue = "none")]
+#![unstable(feature = "error_in_core", issue = "103765")]
 
 #[cfg(test)]
 mod tests;