Add note about ignoring changes above MAX_SAFE_INTEGER

as suggested at #58 (comment)

README.md

@@ -164,6 +164,8 @@ See the [ECMAScript spec](http://www.ecma-international.org/ecma-262/6.0/index.h
 
 3. **Generated patches are not immutable**. The patches generated by JSONPatcherProxy contain reference to the profixied object as the patch `value`. You should either serialize the patch to JSON immediately or deep clone the value it if you want to process it later. If you don't do that, you run the risk that reading the patch will contain changes added after the patch was generated.
 
+4. **Changes for Numbers above `Number.MAX_SAFE_INTEGER` are ignored**. To reduce patch generation noise, JSONPatcherProxy compares if the new value is the same (`===`) as the previous one if so, no patch is generated. Therefore, a change from `Number.MAX_SAFE_INTEGER + 1` to `Number.MAX_SAFE_INTEGER + 2` will not be effectively observed.
+
 ## Specs/tests
 
 #### In browser