Contribution guide recommends cloning both HPCflow and Matflow

[SJaffa]

hpcflow-shared-docs/docs/source/contribute/index.rst

Lines 29 to 39 in 9651bf0

	Checking out hpcflow
	....................
	::
	git clone git@github.com:hpcflow/hpcflow-new.git
	Checking out matflow
	....................
	::
	git clone git@github.com:hpcflow/matflow-new.git

In both HPCflow and MatFlow contribution guide we are recommending to checkout both repos. I think for HPCflow development Matflow definitely shouldn't be mentioned, but I'm not certian if checking out both repos is usefuyl for MatFlow development.

Should we cut it down to just cloning the one you are working on:

Checking out {{ app_name}}
....................
::

   git clone git@github.com:{{ github_user }}/{{ github_repo }}.git

or do we want to keep asking Matflow contributors to check out HPCflow as well?