doc: convert description from attribute to node
When generating manual pages for nmcli the description of different properties is not separated into paragraphs and it does not look nice. That is why i propose these changes.
To have description separated into paragraphs the paragraphs first must
be preserved when parsing them from GTK docs in
./tool/generate-docs-nm-settings-docs-gir.py. There the description
gets parsed and is put into description
subnode (the node above is
property - before these changes the description was attribute of the
property node rather than separate node - this was done to have a better
readable intermediate files).
Along the description
subnode description-docbook
subnode is also
created. It contains the same description as description
subnode but
the paragraphs are further enclosed between <para></para>
tags. This
lets the xsltproc
tool generate manual pages with separated paragraphs.