docbook requiring the installation of minitest

[helgemathee]

I am on Ubuntu 10.04 and found to issues during the installation:

Firstly you need to unzip the installing archive into a folder not called 'docbook', since the installer uses that folder and an error occured if you unzip into ~/docbook

Aside from that, the installation on linux required to install

sudo apt-get install ruby rubygems rake

and finally run

gem install minitest

to provide the missing gem.

I think it would be useful to update the linux installation instructions with this information!

Best regards!