Add description to README.md

Author: devanych

README.md

@@ -1,3 +1,130 @@
 # HTTP Router
 
-The repository is under development, and the description will appear later.
+[![License](https://poser.pugx.org/httpsoft/http-router/license)](https://packagist.org/packages/httpsoft/http-router)
+[![Latest Stable Version](https://poser.pugx.org/httpsoft/http-router/v)](https://packagist.org/packages/httpsoft/http-router)
+[![Total Downloads](https://poser.pugx.org/httpsoft/http-router/downloads)](https://packagist.org/packages/httpsoft/http-router)
+[![GitHub Build Status](https://github.com/httpsoft/http-router/workflows/build/badge.svg)](https://github.com/httpsoft/http-router/actions)
+[![GitHub Static Analysis Status](https://github.com/httpsoft/http-router/workflows/static/badge.svg)](https://github.com/httpsoft/http-router/actions)
+[![Scrutinizer Code Coverage](https://scrutinizer-ci.com/g/httpsoft/http-router/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/httpsoft/http-router/?branch=master)
+[![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/httpsoft/http-router/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/httpsoft/http-router/?branch=master)
+
+This package provides convenient management of HTTP request routing with support for [PSR-7](https://github.com/php-fig/http-message) and [PSR-15](https://github.com/php-fig/http-factory).
+
+## Documentation
+
+* [In English language](https://httpsoft.org/docs/router).
+* [In Russian language](https://httpsoft.org/ru/docs/router).
+
+## Installation
+
+This package requires PHP version 7.4 or later.
+
+```
+composer require httpsoft/http-router
+```
+
+## Usage
+
+```php
+use HttpSoft\Router\RouteCollector;
+
+/**
+ * @var mixed $handler
+ */
+
+$router = new RouteCollector();
+
+// Defining routes.
+$router->get('home', '/', $handler);
+$router->post('logout', '/logout', $handler);
+$router->add('login', '/login', $handler, ['GET', 'POST']);
+
+// Custom regular expressions for placeholder parameter tokens.
+$router->delete('post.delete', '/post/delete/{id}', $handler)->tokens(['id' => '\d+']);
+
+// Generate path '/post/delete/25'
+$router->routes()->path('post.delete', ['id' => 25]);
+// Generate url '//example.com/post/delete/25'
+$router->routes()->url('post.delete', ['id' => 25], 'example.com');
+// Generate url 'https://example.com/post/delete/25'
+$router->routes()->url('post.delete', ['id' => 25], 'example.com', true);
+```
+
+Set the parameter to the default value.
+
+```php
+$router->get('post.view', '/post/{slug}{format}', $handler)
+    ->tokens(['slug' => '[\w\-]+', 'format' => '\.[a-zA-z]{3,}'])
+    ->defaults(['format' => '.html'])
+;
+
+// Generate path '/post/post-slug.html'.
+$router->routes()->path('post.view', ['slug' => 'post-slug']);
+```
+
+Tokens of the route enclosed in `[...]` are considered optional.
+
+```php
+$router->get('post.list', '/posts{[page]}', $handler)
+    ->tokens(['page' =>  '\d+'])
+;
+
+// '/posts/33'
+$router->routes()->path('post.list', ['page' => 33]);
+// '/posts'
+$router->routes()->path('post.list');
+```
+
+If necessary, you can specify a specific host for route matching.
+
+```php
+// Only for example.com
+$router->get('page', '/page', $handler)
+    ->host('example.com')
+;
+
+// Only for subdomain.example.com
+$router->get('page', '/page', $handler)
+    ->host('subdomain.example.com')
+;
+
+// Only for shop.example.com or blog.example.com
+$router->get('page', '/page', $handler)
+    ->host('(shop|blog).example.com')
+;
+```
+
+You can specify routes inside of a group.
+
+```php
+$router->group('/post', static function (RouteCollector $router): void {
+    // '/post/post-slug'
+    $router->get('post.view', '/{slug}', ViewHandler::class)->tokens(['slug' => '[\w-]+']);
+    // '/post' or '/post/page-14'
+    $router->get('post.list', '{[page]}', ListHandler::class)->tokens(['page' =>  'page-\d+']);
+});
+
+// The result will be equivalent to:
+
+$router->get('post.view', '/post/{slug}', ViewHandler::class)->tokens(['slug' => '[\w-]+']);
+$router->get('post.list', '/post{[page]}', ListHandler::class)->tokens(['page' =>  'page-\d+']);
+```
+
+Check matching routes.
+
+```php
+/**
+ * @var mixed $handler
+ * @var Psr\Http\Message\UriInterface $uri
+ * @var Psr\Http\Message\ServerRequestInterface $request
+ */
+
+$router->get('page', '/page/{id}', $handler)->tokens(['id' => '\d+']);
+
+// Match
+$route = $router->routes()->match($request->withUri($uri->withPath('/page/11')));
+$route->getMatchedParameters(); // ['id' => '11']
+
+// Mismatch
+$router->routes()->match($request->withUri($uri->withPath('/page/slug'))); // null
+```