Add a section to "Web IDE (Build)" of how to use library examples

[ScruffR]

It's described how to add a library to own project, but usually I (and I guess others too) test out the lib first before adding it to a new project.

[monkbroc]

Not relevant with libs v2 anymore.

[ScruffR]

Is it? People seem to be missing the USE THIS EXAMPLE button even with v2 libs and I recently was asking myself how would I do build a lib sample with CLI without downloading the lib first.

[monkbroc]

OK then. Reopened!