Documents/Material/Release Notes required for :
I have only found the below link which is useless:
Second how to be a part of Beta Program?
Solved! Go to Solution.
The Beta program is not yet running which is why you aren't finding any materials related to it. In addition, in order to participate in the beta program you'll need to request membership to the program and, as you will be reviewing features that are not yet available, you'll have to have a valid non-disclosure agreement (NDA) in place for your company before participating. I'd guess that most of the beta materials, including videos etc. will be private to the group.
I've got all of the names of the people who responded to the blog post, including you, and will be sending everyone the link to request membership to the group as well as publishing it publically. In the meantime, you can find out about your NDA.