docs(query): make note that filter param to find() can be an ObjectId re: #8268

Author: vkarpov15

lib/model.js

@@ -1963,7 +1963,7 @@ Model.deleteMany = function deleteMany(conditions, options, callback) {
  *     var promise = query.exec();
  *     promise.addBack(function (err, docs) {});
  *
- * @param {Object} filter
+ * @param {Object|ObjectId} filter
  * @param {Object|String} [projection] optional fields to return, see [`Query.prototype.select()`](http://mongoosejs.com/docs/api.html#query_Query-select)
  * @param {Object} [options] optional see [`Query.prototype.setOptions()`](http://mongoosejs.com/docs/api.html#query_Query-setOptions)
  * @param {Function} [callback]

lib/query.js

@@ -1941,7 +1941,7 @@ Query.prototype._find = wrapThunk(function(callback) {
  *     // Using callbacks
  *     Movie.find({ year: { $gte: 1980, $lte: 1989 } }, function(err, arr) {});
  *
- * @param {Object} [filter] mongodb selector. If not specified, returns all documents.
+ * @param {Object|ObjectId} [filter] mongodb selector. If not specified, returns all documents.
  * @param {Function} [callback]
  * @return {Query} this
  * @api public