Improve problem matchers section in README

README.md

@@ -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
@@ -575,19 +577,16 @@ 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
-
-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). 
+#### PHPStan
 
-> Here is an example with `phpstan`.
+PHPStan supports error reporting in GitHub Actions, so no problem matchers are required.
 
 ```yaml
 - name: Setup PHP
@@ -596,10 +595,43 @@ For examples refer to [cs2pr documentation](https://github.com/staabm/annotate-p
  php-version: '7.4'
  tools: phpstan
 
-- name: 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 `phpcs`.
+
+```yaml
+- name: Setup PHP
+ uses: shivammathur/setup-php@v2
+ with:
+ php-version: '7.4'
+ tools: cs2pr, phpcs
+
+- name: Run phpcs
+ run: phpcs -q --report=checkstyle src | cs2pr
+```
+
 ### Examples
 
 Examples of using `setup-php` with various PHP Frameworks and Packages.