docs: --process-dependency-links removal
docs: --process-dependency-links removal

* Removes reference to --process-dependency-links when
  installing Invenio as it is no longer needed. (closes #3401)

Signed-off-by: Javier Martin Montull <ea6b80e26c65acc242d8916fb6eefa01b123cb69@cern.ch>

tiborsimko/invenio,inveniosoftware/invenio,tiborsimko/invenio,inveniosoftware/invenio