Replace README.txt with README.md

Hi made the change requested in scope of the issue also I fixed some phpcs errors and I updated the README following this pattern (https://www.drupal.org/docs/develop/managing-a-drupalorg-theme-module-or...)

Updated Readme file with Proper URL alias

The headings need to be changed to follow Markdown syntax, and the "Contents of this file" portion is not necessary.

Hi @DamienMckenna for me it's everything ok, because I followed the drupal guide. (https://www.drupal.org/docs/develop/managing-a-drupalorg-theme-module-or...)

The existing documentation only describes the suggested syntax for a plaintext README.txt file, not a formatted README.md file, specifically:

It is recommended to take advantage of the newer Markdown format and create a README.md files (instead of README.txt). If you do so, you may want to use more Markdown-features than those used in the example snippets in this template. For instance, Markdown let you create hyperlinks that can be clicked when the README.md is rendered in GitLab or by a compatible program (e.g. Advanced Help).

The Markdown coding standards are still discussed.

The Drupal coding standards, under Naming Conventions / File names, says:

All documentation files should have the file name extension ".txt" to make viewing them on Windows systems easier. Also, the file names for such files should be all-caps (e.g. README.txt instead of readme.txt) while the extension itself is all-lowercase (i.e. txt instead of TXT).

@apderno: That seems to be out of date and misses the point of the newer Markdown syntax files that Gitlab supports; I updated the docs page to reference the newer standard.

Sorry, I will update this file using markdown sintax

I did the requested changes in the comment #14 please revise.

Thanks all,
Code merged.