Fix cloud_functions README typo (#708)

packages/cloud_functions/README.md

diff --git a/packages/cloud_functions/README.md b/packages/cloud_functions/README.md
index dd68d8a..2b209bf 100644
--- a/packages/cloud_functions/README.md
+++ b/packages/cloud_functions/README.md
@@ -32,9 +32,9 @@
 Calling a function:
 
 ```
-dynamic resp = await FirebaseFunctions.instance.call(functionName: 'YOUR_CALLABLE_FUNCTION_NAME');
+dynamic resp = await CloudFunctions.instance.call(functionName: 'YOUR_CALLABLE_FUNCTION_NAME');
 ```
 
 ## Getting Started
 
-See the `example` directory for a complete sample app using Cloud Functions for Firebase.
\ No newline at end of file
+See the `example` directory for a complete sample app using Cloud Functions for Firebase.