Documentation: expand on how to install Igor CA root

[jackjansen]

The whole root CA installation procedure is becoming so incredibly difficult that it is a royal pain in the behind. I'm waiting for some bad guys to post "very useful" scripts that will entice people to completely override SSL security:-(

Instructions need to be put in the documentation.

• Chrome no longer trusts the system root store. Adding certificates may be done with https://chromium.googlesource.com/chromium/src.git/+/master/docs/linux/cert_management.md but maybe you have to add them manually one-by-one through Settings->Security->Advanced.
• Linux doesn't pick up certs from /usr/share/ca-certificates anymore unless you add them to /etc/ca-certificates
• On top of this Python certifi has its own completely separate set of root CAs, and the maintainers frown upon adding your own. Still, https://gist.github.com/jetersen/5efca1278e153aacc8413da71e77494c does still work.

[jackjansen]

Oh yes: Linux update-ca-certificates now frowns upon multiple certificates in one PEM file. So root and intermediate need to be split. Maybe only root is needed?