message: Improve problem matchers section in README
diff: @@ -564,9 +564,11 @@ If you have a number of workflows which setup multiple tools or have many compos
  ### Problem Matchers
  +Problem matchers are `json` configurations which identify errors and warnings in your logs and surface that information prominently in the GitHub Actions UI by highlighting them and creating code annotations.
  +
  #### PHP
  -Setup problem matchers for your `PHP` output by adding this step after the `setup-php` step. This will scan the logs for PHP errors and warnings, and surface them prominently in the GitHub Actions UI by creating annotations and log file decorations.
  +Setup problem matchers for your `PHP` output by adding this step after the `setup-php` step.
  ```yaml
  - name: Setup problem matchers for PHP
  @@ -575,29 +577,59 @@ Setup problem matchers for your `PHP` output by adding this step after the `setu
  #### PHPUnit
  -Setup problem matchers for your `PHPUnit` output by adding this step after the `setup-php` step. This will scan the logs for failing tests and surface that information prominently in the GitHub Actions UI by creating annotations and log file decorations.
  +Setup problem matchers for your `PHPUnit` output by adding this step after the `setup-php` step.
  ```yaml
  - name: Setup problem matchers for PHPUnit
  run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
  ```
  -#### Other Tools
  +#### PHPStan
  +
  +PHPStan supports error reporting in GitHub Actions, so no problem matchers are required.
  +
  +```yaml
  +- name: Setup PHP
  + uses: shivammathur/setup-php@v2
  + with:
  + php-version: '7.4'
  + tools: phpstan
  +
  +- name: Run PHPStan
  + run: phpstan analyse src
  +```
  +
  +#### Psalm
  +
  +Psalm supports error reporting in GitHub Actions with an output format `github`.
  +
  +```yaml
  +- name: Setup PHP
  + uses: shivammathur/setup-php@v2
  + with:
  + php-version: '7.4'
  + tools: psalm
  +
  +- name: Run Psalm
  + run: psalm --output-format=github
  +```
  +
  +#### Tools with checkstyle support
  For tools that support `checkstyle` reporting like `phpstan`, `psalm`, `php-cs-fixer` and `phpcs` you can use `cs2pr` to annotate your code.
  For examples refer to [cs2pr documentation](https://github.com/staabm/annotate-pull-request-from-checkstyle).
  -> Here is an example with `phpstan`.
  +> Here is an example with `phpcs`.
  ```yaml
  - name: Setup PHP
  uses: shivammathur/setup-php@v2
  with:
  php-version: '7.4'
  - tools: phpstan
  + tools: cs2pr, phpcs
  -- name: PHPStan
  - run: phpstan analyse src
  +- name: Run phpcs
  + run: phpcs -q --report=checkstyle src | cs2pr
  ```
  ### Examples
  