Add readme

README.md

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 # LMC Coding Standard for PHP
 
+PHP coding standard used in [LMC](https://www.lmc.eu/en/) projects.
+
+Standard is based on [PSR-2](https://www.php-fig.org/psr/psr-2/) and adds various checks to make sure the code is readable,
+does follow the same conventions and does not contain common mistakes.
+
+We use [EasyCodingStandard] to define and execute checks created for both [PHP-CS-Fixer] and [PHP_CodeSniffer].
+
+**🚧 Please be advised this package is currently under development and anything can change anytime.**
+
+## Installation
+
+```bash
+composer require --dev lmc/coding-standard:dev-master symplify/easy-coding-standard:^4.0@alpha symplify/coding-standard:^4.0@alpha symplify/package-builder:^4.0@alpha symplify/token-runner:^4.0@alpha symplify/better-reflection-docblock:^4.0@alpha
+```
+
+ℹ️ Because we currently depend on `@alpha` version of [EasyCodingStandard], all of its `@alpha` dependencies must temporarily
+also be explicitly required with their stability flag.
+
+## Usage
+
+1. Create `easy-coding-standard.yml` file in root directory of your project and import the LMC code-style rules:
+
+```yaml
+imports:
+    - { resource: 'vendor/lmc/coding-standard/easy-coding-standard.yml' }
+```
+
+2. Run the check command (for `src/` and `tests/` directories):
+
+```bash
+vendor/bin/ecs check src/ tests/
+```
+
+3. Optionally we recommend adding this to `scripts` section of your `composer.json`:
+
+```json
+    "scripts": {
+        "analyze": [
+            "vendor/bin/ecs check src/ tests/ --ansi",
+            "[... other scripts, like PHPStan etc.]"
+        ]
+    }
+```
+
+### Exclude (skip) some checks or files
+
+If you need to exclude some specific check, please refer to the [EasyCodingStandard documentation](https://github.com/Symplify/EasyCodingStandard#exclude-checkers).
+
+If you want to exclude some specific file (or directory) from the checks, you can use `skip` parameter to do so (see [docs](https://github.com/Symplify/EasyCodingStandard#ignore-what-you-cant-fix)).
+⚠️ However **if you define custom `skip` section in your `parameters`, it will overwrite all `skip` rules** from the [imported standard][easy-coding-standard.yml]
+and re-enable various un-intended rules. Until this [ECS limitation](https://github.com/Symplify/Symplify/pull/697#issuecomment-373915457)
+is resolved, the workaround is to redeclare the whole content of the skip section of the main [`easy-coding-standard.yml`][easy-coding-standard.yml] file.
+
 ## Changelog
 For latest changes see [CHANGELOG.md](CHANGELOG.md) file. We follow [Semantic Versioning](http://semver.org/).
 
 ## License
 This library is open source software licensed under the [MIT license](LICENCE.md).
+
+[PHP-CS-Fixer]: https://github.com/FriendsOfPHP/PHP-CS-Fixer
+[PHP_CodeSniffer]: https://github.com/squizlabs/PHP_CodeSniffer
+[EasyCodingStandard]: https://github.com/Symplify/EasyCodingStandard
+[easy-coding-standard.yml]: https://github.com/lmc-eu/php-coding-standard/blob/master/easy-coding-standard.yml