docs: use markdown grammar badges in readme

Signed-off-by: Jack Cherng <jfcherng@gmail.com>

Author: jfcherng

README.md

@@ -1,12 +1,12 @@
 # php-sequence-matcher
 
-<a href="https://travis-ci.org/jfcherng/php-sequence-matcher"><img alt="Travis (.org) branch" src="https://img.shields.io/travis/jfcherng/php-sequence-matcher/master"></a>
-<a href="https://app.codacy.com/project/jfcherng/php-sequence-matcher/dashboard"><img alt="Codacy grade" src="https://img.shields.io/codacy/grade/f7073c3f03784bf39ed41f41f0d3fc8c/master"></a>
-<a href="https://packagist.org/packages/jfcherng/php-sequence-matcher"><img alt="Packagist" src="https://img.shields.io/packagist/dt/jfcherng/php-sequence-matcher"></a>
-<a href="https://packagist.org/packages/jfcherng/php-sequence-matcher"><img alt="Packagist Version" src="https://img.shields.io/packagist/v/jfcherng/php-sequence-matcher"></a>
-<a href="https://github.com/jfcherng/php-sequence-matcher/blob/master/LICENSE"><img alt="Project license" src="https://img.shields.io/github/license/jfcherng/php-sequence-matcher"></a>
-<a href="https://github.com/jfcherng/php-sequence-matcher/stargazers"><img alt="GitHub stars" src="https://img.shields.io/github/stars/jfcherng/php-sequence-matcher?logo=github"></a>
-<a href="https://www.paypal.me/jfcherng/5usd" title="Donate to this project using Paypal"><img src="https://img.shields.io/badge/paypal-donate-blue.svg?logo=paypal" /></a>
+[![Travis (.org) branch](https://img.shields.io/travis/jfcherng/php-sequence-matcher/master)](https://travis-ci.org/jfcherng/php-sequence-matcher)
+[![Codacy grade](https://img.shields.io/codacy/grade/f7073c3f03784bf39ed41f41f0d3fc8c/master)](https://app.codacy.com/project/jfcherng/php-sequence-matcher/dashboard)
+[![Packagist](https://img.shields.io/packagist/dt/jfcherng/php-sequence-matcher)](https://packagist.org/packages/jfcherng/php-sequence-matcher)
+[![Packagist Version](https://img.shields.io/packagist/v/jfcherng/php-sequence-matcher)](https://packagist.org/packages/jfcherng/php-sequence-matcher)
+[![Project license](https://img.shields.io/github/license/jfcherng/php-sequence-matcher)](https://github.com/jfcherng/php-sequence-matcher/blob/master/LICENSE)
+[![GitHub stars](https://img.shields.io/github/stars/jfcherng/php-sequence-matcher?logo=github)](https://github.com/jfcherng/php-sequence-matcher/stargazers)
+[![Donate to this project using Paypal](https://img.shields.io/badge/paypal-donate-blue.svg?logo=paypal)](https://www.paypal.me/jfcherng/5usd)
 
 A longest sequence matcher. The logic is primarily based on the Python [difflib](https://docs.python.org/3/library/difflib.html) package.
 
@@ -19,7 +19,7 @@ A longest sequence matcher. The logic is primarily based on the Python [difflib]
 ## Installation
 
 ```bash
-$ composer require jfcherng/php-sequence-matcher
+composer require jfcherng/php-sequence-matcher
 ```