Replace README.txt with README.md

Thanks @Sonal Gyanani for working on this, Reviewed.

Please review

Hi @chandravilas, Is the changes already merged? Because while applying the patch I'm getting error saying README.md file already exists:

3.diff:9: trailing whitespace.
This Module provides the Split Feature, Split the preview page on different 
3.diff:12: trailing whitespace.
Additionally this module also provide the preview feature on node layout 
3.diff:52: trailing whitespace.
- Enable the module Split Preview go to `Administration > Extend` or by drush 
3.diff:53: trailing whitespace.
  command `drush en split_preview`. 
3.diff:54: trailing whitespace.
- Login as admin user, Go to Administrator menu => Structure => 
Checking patch README.md...
error: README.md: already exists in working directory
Checking patch README.txt...
error: README.txt: No such file or directory

There are some spacing errors also. Need to fix them as well.

ReadMe.txt is updated to ReadMe.md and the content is shown properly. Marking it to RTBC

See comment #7: chandravilas committed ccd4b0c0 on 1.0.x authored by gowthamrajkrishnasamy.

Automatically closed - issue fixed for 2 weeks with no activity.