Preview build of docs on PR

[TC-MO]

We need a docs preview, the idea is to be able to clickthrough docs, while addinf new content & collaborating with people for whom setting up docs locally might be a point of friction.

In an ideal scenario what we are lookg for is to:

• be able to click through whole Platform docs & Academy & API docs
• be able to test that links works properly (at least the ones that send to different parts of the same repository)
• preview should be no longer accessible after merge of PR