[DOCS] - Update Instructions in Readme

[naomi-lgbt]

With #782 having been merged, our instructions in the README.md file are now outdated.

The text needs to be updated to explain that instead of editing the data.json file, the new profile is added by creating a {username}.json file within profiles, replacing {username} with the author's username.

[Pradumnasaraf]

I will we working on this issue :)