fix: rephrase jsdoc and add TODO

Author: ok7sai

src/cdk-experimental/ui-patterns/tree/tree.ts

@@ -168,7 +168,7 @@ export class TreePattern<V> {
   /** The id of the current active item. */
   readonly activedescendant = computed(() => this.focusManager.getActiveDescendant());
 
-  /** Whether the tree is in multi selection mode. */
+  /** Whether the tree is performing a range selection. */
   readonly inSelection = signal(false);
 
   /** The direct children of the root (top-level tree items). */
@@ -378,6 +378,8 @@ export class TreePattern<V> {
     });
   }
 
+  // TODO(ok7sai): add `setDefaultState` method.
+
   /** Handles keydown events on the tree. */
   onKeydown(event: KeyboardEvent) {
     if (!this.disabled()) {