chore: Add explanation comment

Author: Techassi

crates/stackable-versioned-macros/src/codegen/module.rs

@@ -41,7 +41,10 @@ impl Module {
             return quote! {};
         }
 
-        // TODO (@Techassi): Leave comment explaining this
+        // If the 'preserve_module' flag is provided by the user, we need to change the visibility
+        // of version modules (eg. 'v1alpha1') to be public, so that they are accessible inside the
+        // preserved (wrapping) module. Otherwise, we can inherit the visibility from the module
+        // which will be erased.
         let version_module_vis = if self.preserve_module {
             &Visibility::Public(Pub::default())
         } else {