Update comment of clippy_lints/src/unwrap.rs

Co-authored-by: Samuel Tardieu <[email protected]>

Author: relaxcn

clippy_lints/src/unwrap.rs

@@ -292,7 +292,7 @@ impl<'tcx> Visitor<'tcx> for UnwrappableVariablesVisitor<'_, 'tcx> {
         if expr.span.in_external_macro(self.cx.tcx.sess.source_map()) {
             return;
         }
-        // Skip checking all expressions inside closures
+        // Skip checking inside closures since they are visited through `Unwrap::check_fn()` already.
         if matches!(expr.kind, ExprKind::Closure(_)) {
             return;
         }