[www-api] Update the "How to contribute" redirect url
[www-api] Update the "How to contribute" redirect url

Change-Id: I2960ff047b58cfc46ce864190379376b059af868

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals