issues in the installation guides

[fenrog]

• Formatting error of URLs. []() may not have a line break inbetween.
• Path not always consistently set and displayed.
• Raspbian OS bullseye has ntp installed as systemd-timesyn, not as ntpd. Describe how to verify ntp is running.
• venv installation doesn't work neither with Raspbian OS nor with Ubuntu. sudo python3 -m pip install venv should read as sudo python3 -m pip install virtualenv.
• Chapter 3.1 python -m pip install -U pip wheel setuptools should read as python3 -m pip install -U pip wheel setuptools

[fenrog]

ready for merge with https://github.com/sberl/supersid/pull/81