Add information about the shi to the README.md

[Guzz-T]

To ensure that the documentation was correct, I also had to:

• Add unit to Base
• Integrate the scripts from SHI to the CLI

First guess for #214

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
luxtronik
__init__.py	236	13	94%	89–102, 251–252, 257
__main__.py	25	25	0%	3–62
datatypes.py	391	2	99%	57, 127
discover.py	58	1	98%	62
parameters.py	24	1	96%	1223
luxtronik/scripts
__init__.py	16	16	0%	3–28
discover_shi.py	60	60	0%	8–98
dump_changes.py	43	43	0%	7–85
dump_luxtronik.py	26	26	0%	6–52
dump_shi.py	19	19	0%	7–40
performance_shi.py	63	63	0%	7–89
watch_shi.py	38	38	0%	7–85
luxtronik/shi
contiguous.py	135	2	99%	261–262
TOTAL	2194	309	86%

Tests	Skipped	Failures	Errors	Time
363	0 💤	0 ❌	0 🔥	14.099s ⏱️

[kbabioch]

The link could probably be relative:

Suggested change

	[luxtronik/shi/README.md](https://github.com/Bouni/python-luxtronik/blob/master/luxtronik/shi/README.md).
	[luxtronik/shi/README.md](luxtronik/shi/README.md)

If this doesn't work, it should be added to the bottom of the file as reference instead of exploding the line length.

[Guzz-T]

Done

[kbabioch]

Wow, didn't expect you to work on this one, so thank you very much ;-).

From my point of view, it's superb, happy to merge. Added minor nit-picking comments, feel free to address them (or ignore them ;-)).