Added  python and HTML/CSS course links for beginners as part of hacktoberfest2020 (PR resubmission) (#4298)

* Added a python course link

As  part of hacktoberfest20

* updated free-courses-en.md with a new link

As  per the requirements the link is alphabetically added

* Added an HLML&CSS course link

* Changed the extra blanklines

* updated with platform and tutor name

* updated the course list

* Updated the file again

* updated the list