If you are logged in, you can now subscribe to the Products, Specification and General forums with a button at the top of the page. Note that you can also subscribe to sub-forums and topics so if you just want to receive entries about the HiKey or DragonBoard 410c boards, you can subscribe to those individually, or subscribing to Products will give you everything about both.
One other minor update: when we launched the HiKey forum, we had three sections: beginners, advanced and troubleshooting. We have combined these into the single HiKey forum after feedback from several people.