Put more emphasis on Allegro in the README.

Added Allegro license to the README.

README.md

@@ -2,20 +2,20 @@
 
 ## Content
 
-- [Introduction](#Introduction)
+- [Introduction](#introduction)
-- [Additional Rules](#Additional-Rules)
+- [Additional Rules](#additional-rules)
-   * [Implementation](#Implementation)
+   * [Implementation](#implementation)
-   * [Definition](#Definition)
+   * [Definition](#definition)
-- [Building](#Building)
+- [Building](#building)
-   * [Using Allegro](#Using-Allegro)
+   * [Using Allegro](#using-allegro)
-- [Sources](#Sources)
+- [Sources](#sources)
-- [Licenses (third party)](#Licenses)
+- [Licenses (third party)](#licenses)
-   * [Go-SDL2](#Go-SDL2)
+   * [Go-SDL2](#go-sdl2)
-   * [SDL 2.0](#SDL-2.0)
+   * [SDL 2.0](#sdl-2.0)
-   * [Allegro 5](#Allegro-5)
+   * [Allegro 5](#allegro-5)
-   * [Fira Mono font](#Fira-Mono-font)
+   * [Fira Mono font](#fira-mono-font)
-   * [Escher font](#Escher-font)
+   * [Escher font](#escher-font)
-   * [Escheresk font](#Escheresk-font)
+   * [Escheresk font](#escheresk-font)
    * [fauxgl](#fauxgl)
    * [draw2d](#draw2d)
    * [go-colurful](#go-colurful)