Document condition.

clippy_lints/src/cargo_common_metadata.rs

@@ -93,6 +93,7 @@ impl LateLintPass<'_> for CargoCommonMetadata {
         let metadata = unwrap_cargo_metadata!(cx, CARGO_COMMON_METADATA, false);
 
         for package in metadata.packages {
+            // we want to skip the lint if publish is `None` (`publish = false`) or if the vector is empty (`publish = []`)
             if package.publish.as_ref().filter(|publish| publish.is_empty()).is_none() || self.ignore_publish {
                 if is_empty_vec(&package.authors) {
                     missing_warning(cx, &package, "package.authors");