docs: Add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,39 @@
+# Contributing
+
+This doc is intended for contributors to `sdk-php` (hopefully that's you!)
+
+All contributors must complete the Temporal Contributor License Agreement (CLA) before changes can be merged. A link to the CLA will be posted in the PR.
+
+## Development environment
+
+- [PHP 8.1+](https://www.php.net/downloads.php)
+- [Composer](https://getcomposer.org/download/)
+
+## Build
+
+```bash
+composer install              # Downloads regular dependencies
+composer run get:binaries     # Downloads dependencies for local development
+pecl install grpc             # Required by the Temporal client
+pecl install protobuf         # Improves performance of protobuf serialization
+```
+
+## Test
+
+```bash
+composer run test:unit        # Unit tests
+composer run test:func        # Functional tests
+composer run test:arch        # Architecture tests
+composer run test:accept      # All acceptance tests
+composer run test:accept-fast # All acceptance tests except the slow ones
+composer run test:accept-slow # Only the slow acceptance tests
+```
+
+## Quality control
+
+```bash
+composer run cs:diff          # Show code style violations (dry run)
+composer run cs:fix           # Auto-fix code style violations
+composer run psalm            # Run static analysis
+composer run psalm:baseline   # Update the Psalm baseline file
+```

README.md

@@ -140,6 +140,10 @@ Web UI will be available at `http://localhost:8000`.
 For advanced autocomplete while coding in PHPStorm, use [Meta Storm plugin](https://github.com/xepozz/meta-storm-idea-plugin).
 The plugin provides better autocomplete and links Workflow and Activity when writing and debugging code.
 
+## Contibuting
+
+We'd love your help improving the Temporal PHP SDK. Please review our [contribution guidelines](./CONTRIBUTING.md).
+
 ## Resources
 
 Read the docs