Replace README.txt to README.md and update README.md

Created MR , please review.

Thank you.

This looks great but it's a duplicate of #3130522: README - Documentation does not follow Drupal Documentation standards → . Do you want to apply these changes to that ticket instead?

The patch works fine. Moving it to RTBC

As mentioned before this duplicates work done in #3130522: README - Documentation does not follow Drupal Documentation standards → . That ticket has already been open for a long time to update the Readme. I will close this one so we can focus the attention on a single ticket.