docs: Add '/docs' directory to 'README.rst'
docs: Add '/docs' directory to 'README.rst'

Add a link to the '/docs' directory and remove the link to the wiki.

Change-Id: I42e598a5fbbcbb1eaa2f87db6398123d13b0e452

open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis