docs(model): make create() docs use async/await, and add another wa…

…rning about how `create()` with options requires array syntax

Fix #9280

lib/model.js

@@ -2948,26 +2948,16 @@ Model.findByIdAndRemove = function(id, options, callback) {
  *
  * ####Example:
  *
- *     // pass a spread of docs and a callback
- *     Candy.create({ type: 'jelly bean' }, { type: 'snickers' }, function (err, jellybean, snickers) {
- *       if (err) // ...
- *     });
- *
- *     // pass an array of docs
- *     var array = [{ type: 'jelly bean' }, { type: 'snickers' }];
- *     Candy.create(array, function (err, candies) {
- *       if (err) // ...
- *
- *       var jellybean = candies[0];
- *       var snickers = candies[1];
- *       // ...
- *     });
- *
- *     // callback is optional; use the returned promise if you like:
- *     var promise = Candy.create({ type: 'jawbreaker' });
- *     promise.then(function (jawbreaker) {
- *       // ...
- *     })
+ *     // Insert one new `Character` document
+ *     await Character.create({ name: 'Jean-Luc Picard' });
+ * 
+ *     // Insert multiple new `Character` documents
+ *     await Character.create([{ name: 'Will Riker' }, { name: 'Geordi LaForge' }]);
+ * 
+ *     // Create a new character within a transaction. Note that you **must**
+ *     // pass an array as the first parameter to `create()` if you want to
+ *     // specify options.
+ *     await Character.create([{ name: 'Jean-Luc Picard' }], { session });
  *
  * @param {Array|Object} docs Documents to insert, as a spread or array
  * @param {Object} [options] Options passed down to `save()`. To specify `options`, `docs` **must** be an array, not a spread.