Fix CONTRIBUTING.md

Author: kobylynskyi

CONTRIBUTING.md

@@ -17,15 +17,16 @@ Before sending your pull requests, make sure you followed this list:
 Please follow the steps below in order to make the changes:
 
 1. Clone the repository and open it in your favourite IDE.
-2. Make code changes to the core library of `graphql-java-codegen`.
-3. If changes are required in the plugin code, then **build** and **install** `graphql-java-codegen` first.
+2. Checkout **develop** branch.
+3. Make code changes to the core library of `graphql-java-codegen`.
+4. If changes are required in the plugin code, then **build** and **install** `graphql-java-codegen` first.
 
    ```shell script
    # This will install the library (including your recent changes) in your local maven repository.
    ./gradlew clean build publishToMavenLocal
    ```
 
-4. Build the plugin project with updated `graphql-java-codegen` library.
+5. Build the plugin project with updated `graphql-java-codegen` library.
 
    ```shell script
    # Build Gradle plugin
@@ -36,8 +37,8 @@ Please follow the steps below in order to make the changes:
    mvn clean verify 
    ```
 
-5. Make changes to the plugin code
-6. Install the plugin (copy to your local maven repository).
+6. Make changes to the plugin code
+7. Install the plugin (copy to your local maven repository).
 
    ```shell script
    # Install Gradle plugin
@@ -48,4 +49,4 @@ Please follow the steps below in order to make the changes:
    mvn clean install 
    ```
 
-7. Make sure that `example` projects are compiling and running.
+8. Make sure that `example` projects are compiling and running.