[basics] Perhaps break out applied parts and move to other modules

[dbosk]

Some parts, e.g. about passwords, perhaps should be moved to other modules:

• passwords to passwd module?

[dbosk]

Or at least split it into basics and then examples of applications?

[dbosk]

It's good to give some example uses too. But some of the applications would also be good to have in the other modules too.

[dbosk]

I'll close the issue once the relevant applied parts have been copied to the modules where they fit.