Render submodule warning less ambiguous with the no mention warning

Author: Urgau

src/handlers/check_commits/modified_submodule.rs

@@ -1,6 +1,6 @@
 use crate::github::FileDiff;
 
-const SUBMODULE_WARNING_MSG: &str = "These commits modify **submodules**.";
+const SUBMODULE_WARNING_MSG: &str = "Some commits in this PR modify **submodules**.";
 
 /// Returns a message if the PR modifies a git submodule.
 pub(super) fn modifies_submodule(diff: &[FileDiff]) -> Option<String> {