Update POLICY.md

Author: GsCommand

POLICY.md

@@ -123,7 +123,7 @@ Every release MUST:
 
 The Protocol Commons operates under a strict immutability rule:
 
-> No schema, once published in a versioned directory, may be altered in-place.
+ No schema changes, once published in a versioned directory, may be altered in-place.
 
 All corrective or breaking changes MUST be handled via new versioned directories.
 
@@ -148,3 +148,4 @@ Removal is only permitted for verified security risks and MUST include a migrati
 
 
 
+