Update grammar

[spagh-eddie]

This changes text in content/en/about-getting-started.md. It removes the comma (and the "right") from You add documentation comments ..., right alongside the code itself to be You add documentation comments ... alongside the code itself.

I built the HTML following the instructions in the README by running npm install -g gulp; npm install -g bower; npm install; bower install; gulp. If the changes to the rest of the HTML files and package.lock is incorrect, please let me know!