Update README.txt to README.md according Readme Template Suggestions

Hi

I reviewed your MR!2 and the project link should be in the correct format [project page](https://www.drupal.org/project/https://www.drupal.org/project/simple_megamenu) to https://www.drupal.org/project/simple_megamenu and as per README.md Text manually word-wrapped within around 80 cols.

Thank you

Thank you @kenyoOwen
I have resolved issues.

Hi ravi,

I reviewed your changes in behalf of ken, and the README file now looks good.

RTBC +1 from me.

Retaining the status to needs review to givr others the chance to review.