HPCC-9930 Updated list of dependencies for installing from source

Alterations to sourcedoc.xml to include extra dependencies and
installation notes.

Fix missing <para>

Added docs/Installing_from_Source with required sub files to build
'Installing_from_Source.pdf. This just is a copy of sourcedoc.xml.

A line was added to docs/CMakeLists.txt to produce the above directory.

Signed-off-by: jamienoss <james.noss@lexisnexis.com>