Polishing Setup Instructions.

[ndaelman-hu]

While preparing Tutorial 14, I noticed some small points that could further remove friction when setting up:

• Mention that cruft is a python package that should be installed. This is especially for those using cruft for the 1st time.
• Suggest people to go with Apache 2.0 license (so it is most compatible with the NOMAD license). Maybe also make it the default option.
• Give specifications on what should happen with the README.md, i.e. should it stay untouched, or may it be updated to reflect the objective of the plugin, as most README's do. My assumption is that the docs and entry point metadata rather serve these respective goals. Still best to be very clear here.
• Point out where the “Use this template” button.

[blueraft]

Sorry, I didn't see this earlier. I'll have a look