Rework README.txt as a Markdown file

Please rework the existing content using Markdown syntax rather than replacing it.

@damienmckenna
Ok Checking on it

Sorry folks, but there needs to be more work on this beyond renaming the file.

You've both opened and worked on a lot of issues like this for different projects, please put a little more work into them beyond just renaming a file, a plain text file renamed to ".md" is wasted time.

Will check it.
But when we are renaming the Readme file to .md format it automatically detects the Markdown format and adapts according to that.
So we are adding it and verifying in the
Can you please mention which way it can be improved instead of Renaming in the file.

@damienmckenna
Can you please check now.
Have used the format as from the https://www.drupal.org/docs/develop/managing-a-drupalorg-theme-module-or...

Here is a summary of the preferred format for README.md:

Headings in all caps.
Headings underlined with ===/--- to the length of the heading, followed by a blank line.
Two lines prior to headings (except the first one).
Bullets denoted by asterisks (*) with hanging indents.
Numbered lists indented 4 spaces.
Bulleted lists indented 1 space.
Text manually word-wrapped within around 80 cols.

Thank you, that's better.

I'm going to review the document as a whole as there are some other changes I think we should make to make it work better as a Markdown file.

Committed. Thank you.