document new 'method' param

Author: StevePotter

README.md

@@ -53,8 +53,9 @@ The only React Native http post file uploader with android and iOS background su
 import Upload from 'react-native-background-upload'
 
 const options {
-  url: 'https://myservice.com/path/to/post'
-  path: 'file://path/to/file/on/device'
+  url: 'https://myservice.com/path/to/post',
+  path: 'file://path/to/file/on/device',
+  method: 'POST',
   headers: {
     'my-custom-header': 's3headervalueorwhateveryouneed'
   }

index.js

@@ -51,6 +51,7 @@ Options object:
   url: string.  url to post to.
   path: string.  path to the file on the device
   headers: hash of name/value header pairs
+  method: HTTP method to use.  Default is "POST"
 }
 
 Returns a promise with the string ID of the upload.  Will reject if there is a connection problem, the file doesn't exist, or there is some other problem.