Add more details to robot docs

[EduKav1813]

The problem you're addressing (if any)

The current version of the robot documentation does not provide all necessary information that may help to develop or debug tests.

Describe the solution you'd like

Add the following information to the robot documentation:

1. Type hints for the arguments. If I see something like: Arguments: item it would help to know what type it is.
2. The type hints for the return values. The same as in the previous one.
3. Not all keywords have Documentation. Even if their name may be self-descriptive, it could confuse new users.

Where is the value to a user, and who might that user be?

Provide more relevant context for test developers.

Describe alternatives you've considered

No response

Additional context

No response

[m-iwanicki]

Not sure if it's correct place or if it should be in it's own issue but we should probably at least somewhat standardize keyword description format. I would like if we not only had type hints of arguments and return values but also description of what this variable is for.

I'd also like if each description had requirements of when it can be used and maybe some side effects of using keyword e.g. whether keyword needs to be used inside Linux shell or during booting (e.g. after power on or reboot), whether using this keyword ends in reboot (especially if it's not easily deducible from description/name). Often keyword doesn't need e.g. Power On used before it because it either uses it by itself or uses another keyword that uses it but in those cases it might be hard to know without diving deeply inside each keyword. Would help with contributing.md:

reduce the number of unnecessary power events, so tests can finish quicker