Wiki: Using firejail from git

[rusty-snake]

Issue for discussions about https://github.com/netblue30/firejail/wiki/Using-firejail-from-git.

[glitsj16]

I added a routine to the Debian/Ubuntu section referring to our update_deb.sh script from contrib and opened #3450 for review. As mentioned there I don't exactly know how to patch firejail.config to accomodate https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=916920. Or even whether we want that. Would be nice to get input on how to best proceed on the latter.

[curiosityseeker]

I added some more configuration options.

[rusty-snake]

sudo sed -i 's/# force-nonewprivs no/force-nonewprivs yes/' /etc/firejail/firejail.config

1. We could add more (restrict-network, ...)
2. We should add a warning that make install overrides /etc/firejail/firejail.config.

[glitsj16]

I added the warning for (2) cfr. @rusty-snake's suggestion.

[rusty-snake]

#4450