Replace previous links in the documentation

Replace previous links in the documentation

Due to the recent effort of converting the docs from markdown
to rst format, the old links in the documentation aren't working.
This change updates the previous links and adds minor updates.

Signed-off-by: Rihab Banday <rihab.banday@ericsson.com>
Change-Id: I8f8d5509a0d0c2bee84e49553e58baf276004544
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/73228
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Reviewed-by: Dan Xu <xudan16@huawei.com>
Reviewed-by: Georg Kunz <georg.kunz@ericsson.com>