Added info about using local repo in readme

Author: dbarsukov

README.md

@@ -34,7 +34,7 @@ Lastly, if you just want to see the module in action and run the tests yourself
 Then, go to the project directory and run:
 
 ```shell
-vendor/bin/codecept run Functional
+composer test
 ```
 
 ### Create Unit Suite or Acceptance Suite
@@ -44,3 +44,24 @@ To create [Unit Tests](https://codeception.com/docs/05-UnitTests) or [Acceptance
 vendor/bin/codecept generate:suite Unit
 vendor/bin/codecept generate:suite Acceptance
 ```
+
+### Create a Test
+
+```shell
+php vendor/bin/codecept generate:cest Functional <Name>
+```
+
+### Using local code for tests
+
+Assuming you checked out module-symfony into the same directory with symfony-module-tests, you can test your branch. Add following code into composer.json and run `composer update`. Don't forget to revert composer.json and composer.lock before commit.
+```
+{
+  // ...
+  "repositories": [
+    {
+      "type": "path",
+      "url": "../module-symfony"
+    }
+  ]
+}
+```