docs: fix liuk and add coverage badge

Author: viceice

README.md

@@ -1,6 +1,7 @@
 [![build](https://github.com/visualon/cssparser/actions/workflows/build.yml/badge.svg)](https://github.com/visualon/cssparser/actions/workflows/build.yml)
 [![VisualOn.CSSParser](https://img.shields.io/nuget/v/VisualOn.CSSParser?label=VisualOn.CSSParser)](https://www.nuget.org/packages/VisualOn.CssParser)
 [![VisualOn.CSSParser.ExtendedLESSParser](https://img.shields.io/nuget/v/VisualOn.CSSParser.ExtendedLESSParser?label=VisualOn.CSSParser.ExtendedLESSParser)](https://www.nuget.org/packages/VisualOn.CssParser.ExtendedLESSParser)
+[![codecov](https://codecov.io/gh/visualon/cssparser/branch/main/graph/badge.svg?token=EEGfq3zpqS)](https://codecov.io/gh/visualon/cssparser)
 ![LICENSE](https://img.shields.io/github/license/visualon/cssparser)
 
 # CSS Parser 
@@ -10,10 +11,10 @@ This is a fork from [Dan Roberts](https://bitbucket.org/DanRoberts/cssparser).
 A simple CSS and LESS parser to categorise strings of content and optionally generate a hierarchical representation of it.
 
 ## Changes
-See [Releases](/visualon/cssparser/releases)
+See [Releases](https://github.com/visualon/cssparser/releases)
 
 ## License
-[MIT License](LICENSE)
+[MIT License](LICENSE.txt)
 
 
 ### Howto