Add storage documentation

Author: chrisbianca

docs/api/storage

@@ -0,0 +1,91 @@
+
+# Storage
+
+Firestack mimics the [Web Firebase SDK Storage](https://firebase.google.com/docs/storage/web/start), whilst
+providing some iOS and Android specific functionality.
+
+All Storage operations are accessed via `storage()`.
+
+## Uploading files
+
+### Simple
+
+```javascript
+firestack.storage()
+    .ref('/files/1234')
+    .putFile('/path/to/file/1234')
+    .then(uploadedFile => {
+        //success
+    })
+    .catch(err => {
+        //Error
+    });
+```
+
+### Listen to upload state
+
+```javascript
+const unsubscribe = firestack.storage()
+                        .ref('/files/1234')
+                        .putFile('/path/to/file/1234')
+                        .on('state_changed', snapshot => {
+                            //Current upload state
+                        }, err => {
+                            //Error
+                            unsubscribe();
+                        }, uploadedFile => {
+                            //Success
+                            unsubscribe();
+                        });
+```
+
+## Downloading files
+
+### Simple
+
+```javascript
+firestack.storage()
+    .ref('/files/1234')
+    .downloadFile('/path/to/save/file')
+    .then(downloadedFile => {
+        //success
+    })
+    .catch(err => {
+        //Error
+    });
+```
+
+### Listen to download state
+
+```javascript
+const unsubscribe = firestack.storage()
+                        .ref('/files/1234')
+                        .downloadFile('/path/to/save/file')
+                        .on('state_changed', snapshot => {
+                            //Current download state
+                        }, err => {
+                            //Error
+                            unsubscribe();
+                        }, downloadedFile => {
+                            //Success
+                            unsubscribe();
+                        });
+```
+
+## TODO
+
+There are a few methods which have not yet been implemented for Storage:
+
+### Reference
+- put()
+- putString()
+
+### UploadTask
+- cancel()
+- pause()
+- resume()
+
+### DownloadTask
+- cancel()
+- pause()
+- resume()

docs/api/storage.md

@@ -66,8 +66,6 @@ export default class StorageRef extends ReferenceBase {
   }
 
   //Additional methods compared to Web API
-
-  //TODO: Listeners
   /**
    * Downloads a reference to the device
    * @param {String} filePath Where to store the file