Add doc and CHANGES.md update.

CHANGES.md

@@ -15,6 +15,7 @@
 - Changed how `TilesetOptions::forbidHoles` works so that it loads much more quickly, while still guaranteeing there are no holes in the tileset.
 - Added `frameNumber` property to `ViewUpdateResult`.
 - Added getters for the `stride` and `data` fields of `AccessorView`.
+- Added `startNewFrame` method to `ITileExcluder`.
 
 ##### Fixes :wrench:
 

Cesium3DTilesSelection/include/Cesium3DTilesSelection/ITileExcluder.h

@@ -11,7 +11,20 @@ class Tile;
 class ITileExcluder {
 public:
   virtual ~ITileExcluder() = default;
+
+  /**
+   * @brief Indicates the start of a new frame, initiated with a call to {@link Tileset::updateView}.
+   */
   virtual void startNewFrame() noexcept {}
+
+  /**
+   * @brief Determines whether a given tile should be excluded.
+   *
+   * @param tile The tile to test
+   * @return true if this tile and all of its descendants in the bounding volume
+   * hiearchy should be excluded from loading and rendering.
+   * @return false if this tile should be included.
+   */
   virtual bool shouldExclude(const Tile& tile) const noexcept = 0;
 };