Adds documentation about 2.0.0

Author: flovilmart

2.0.0.md

@@ -0,0 +1,77 @@
+# Upgrading Parse SDK to version 2.0.0
+
+With Parse SDK 2.0.0, gone are the backbone style callbacks and Parse.Promises.
+
+Instead, the Parse SDK 2.0.0 uses native promises in the browser, node and react native that allows for a more standard API.
+
+Migrating to native Promises should be straightforward, we'll recap the different changes:
+
+## `.done()` and `.fail()` continuations
+
+With native promises, `.done` and `.fail` don't exist and are replaces by `.then` and `.catch`
+
+```js
+// before
+const query = new Parse.Query();
+query.find()
+.done((results) => {
+
+})
+.fail((error) => {
+
+});
+
+// after
+query.find()
+.then((results) => {
+
+})
+.catch((error) => {
+
+});
+```
+
+## `.always()` is replaced by `.finally()`
+
+```js
+// before
+const query = new Parse.Query();
+query.find()
+.always((result) => {
+
+});
+
+// after
+query.find()
+.finally((result) => {
+
+});
+```
+
+## `new Parse.Promise()`
+
+With native promises, the constructor is different, you will need to update to the native constructor which requires moving the code around.
+
+```js
+// before
+const promise = new Promise();
+doSomethingAsync((error, success) => {
+  if (error) { promise.reject(error); }
+  else { promise.resolve(success); }
+});
+return promise;
+
+// after
+return new Promise((resolve, reject) => {
+  doSomethingAsync((error, success) => {
+    if (error) { reject(error); }
+    else { resolve(success); }
+  });
+});
+```
+
+## Static methods
+
+- `Parse.Promise.as` is replaced by `Promise.resolve`
+- `Parse.Promise.error` is replaced by `Promise.reject`
+- `Parse.Promise.when` is replaced by `Promise.all`