Actualize docs: use docker for exec commands.

README.md

@@ -3,6 +3,7 @@ Simple bitmask implementation
 
 [![License](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 [![Packagist](https://img.shields.io/packagist/v/aliance/bitmask.svg)](https://packagist.org/packages/aliance/bitmask)
+![PHP Version](https://img.shields.io/badge/PHP-7.4-green.svg)
 [![Build Status](https://travis-ci.org/Aliance/Bitmask.svg?branch=master)](https://travis-ci.org/Aliance/Bitmask)
 [![Code Coverage](https://scrutinizer-ci.com/g/Aliance/Bitmask/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/Aliance/Bitmask/?branch=master)
 
@@ -11,24 +12,26 @@ About
 
 Bitmask is a simple PHP implementation of bitwise operations for creating masks.
 Can be used for some flags implementation.
-Currently supported PHP version: >= 7.4
+Supports only 64 bits (from 0 to 63) on x64 platforms.
 
 Installation
 ---
 
 Install the latest version with composer:
 
 ```bash
-$ composer require aliance/bitmask
+composer require aliance/bitmask
 ```
 
 Usage
 ---
 
 See usage in [sample](./example/example.php) file.
 
+```bash
+docker run -it --rm -v "$PWD":/usr/src/bitmask -w /usr/src/bitmask php:7.4-cli php example/example.php  
+```
 ```
-Aliance/Bitmask $ php -f example/example.php 
 Check user for all access levels:
 Create: no
 Read: no
@@ -48,7 +51,10 @@ Delete: no
 Tests
 ---
 
-For completely tests running just call `composer exec phpunit`.
+For completely tests running just call `composer exec phpunit` or use
+```bash
+docker run -it --rm -v "$PWD":/usr/src/bitmask -w /usr/src/bitmask php:7.4-cli php ./vendor/bin/phpunit 
+```
 
 License
 ---