Documentation for building from source doesn't work

[dyfrgi]

On https://www.ddcutil.com/building/, in the section on building from a tarball, it says:

issue the commands:

# ./configure
# make
# sudo make install

However, a configure script is not packaged in the current (2.1.0) tarball.

There's also one build dependency not mentioned, jansson (libjansson-dev).

[rockowitz]

I've updated the build instructions and made a few other changes on that page. Detailed rework will have to wait until after the upcoming 2.1.1 release. Thanks for pointing this out. The web site more generally needs updating - many pages have become out of date, and the contents of release notes are only partially integrated with the main pages.