Minor wording changes throughout the code

[fedarko]

• The JS code uses tip 215 times and leaf 96 times. We should settle on using just one of these terms, to make it easier to use the code.

• The selection menu module is named SelectedNodeMenu, but the file is named select-node-menu.js. Would be good to make this consistent.

These are just minor things that will make maintaining the project a bit easier.

[piyushswain]

@fedarko Can I start working on this ?

[fedarko]

@ps9793 Sure, if you'd be interested in working on this we're happy to take pull requests!

[96RadhikaJadhav]

@fedarko Is this issue still open? I would like to work on it.

[ElDeveloper]

Thanks so much @96RadhikaJadhav, I've assigned you to this issue.