Rollup merge of #111572 - kpreid:mdi, r=compiler-errors

Document that `missing_copy_implementations` and `missing_debug_implementations` only apply to public items.

I encountered #111359 (fixed) and noticed that the documentation didn't say that it was _intended_ that `missing_debug_implementations` only applies to public items. This PR fixes that, and makes the same wording change to `missing_copy_implementations` which has the same condition.

I chose the words to also be similar to `missing_docs` which already had such a remark.

compiler/rustc_lint/src/builtin.rs

@@ -611,7 +611,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
 
 declare_lint! {
     /// The `missing_copy_implementations` lint detects potentially-forgotten
-    /// implementations of [`Copy`].
+    /// implementations of [`Copy`] for public types.
     ///
     /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
     ///
@@ -729,7 +729,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
 
 declare_lint! {
     /// The `missing_debug_implementations` lint detects missing
-    /// implementations of [`fmt::Debug`].
+    /// implementations of [`fmt::Debug`] for public types.
     ///
     /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html
     ///