Provide a better example on how to use the tool with shivammathur… (#12)

* Provide a better example on how to use the tool with shivammathur/setup-php

Since they officially support `cs2pr`

* fix typo

* Update README.md

Co-authored-by: Markus Staab <maggus.staab@googlemail.com>

Author: tristanbes

README.md

@@ -79,9 +79,11 @@ you might instead try
 
 ## Example GithubAction workflow
 
+
+If you're using `shivammathur/setup-php` to setup PHP, `cs2pr` binary is shipped within:
+
 ```
 # ...
-
 jobs:
     phpstan-analysis:
       name: phpstan static code analysis
@@ -93,6 +95,24 @@ jobs:
             with:
                 php-version: 7.3
                 coverage: none # disable xdebug, pcov
+                tools: cs2pr
+          - run: |
+                composer install # install your apps dependencies
+                vendor/bin/phpstan analyse --error-format=checkstyle | cs2pr
+```
+
+If you're use a custom PHP installation, then your project needs to require `staabm/annotate-pull-request-from-checkstyle`
+
+```
+# ...
+jobs:
+    phpstan-analysis:
+      name: phpstan static code analysis
+      runs-on: ubuntu-latest
+      steps:
+          - uses: actions/checkout@v2
+          - name: Setup PHP
+            run: # custom PHP installation 
           - run: |
                 composer install # install your apps dependencies
                 composer require staabm/annotate-pull-request-from-checkstyle # install cs2pr