Please add https://www.openhwgroup.org/core-v-devkits/ landing page

Created by: DBees

Please add the landing page for https://www.openhwgroup.org/core-v-devkits/. This needs to be added this week and go live ideally on Sunday June 19

The content is https://docs.google.com/document/d/159bGcqvPy64pY1Fk2JRJHEdAEbUtW0bHWznOU33SHBk/edit#

There will be some minor updates coming to the content, see comments included.