docs: Update comments on patch

Author: drklee3

mutable_tree.go

@@ -771,11 +771,14 @@ func (tree *MutableTree) SaveVersion() ([]byte, int64, error) {
 		}
 	}
 
-	// PATCH for backwards compatibility:
-	// On InitialVersion, this is a new tree.
-	// Add a reference node from InitialVersion -> 1 (root node)
-	// Note: Node version != nodekey.Version due to patch
+	// Addition to node version patch for backwards compatibility:
+	// This is to resolve queries at InitialVersion, loading the tree at
+	// InitialVersion when the root node has version 1.
+	// Note: version != nodekey.Version due to patch.
 	if tree.ndb.opts.InitialVersion > 0 && version == int64(tree.ndb.opts.InitialVersion) {
+		// SaveRoot is meant for saving a tree when there are no updates, which
+		// simply creates a reference node to the root node. We reuse this to
+		// create a reference node from InitialVersion -> 1 (root node).
 		if err := tree.ndb.SaveRoot(version, tree.root.nodeKey); err != nil {
 			return nil, 0, err
 		}