automatically run site deploy on new tag creation

[akellbl4]

It would be convenient to run deploy on new release creation. It will be updated with new docs and a version in the header.

cc @umputun @paskal

[umputun]

this is in place and it does site's deploy on master change

[akellbl4]

@umputun it better be by tag or manually (for occasional fixes). Otherwise, we could have docs for the next version, not for the current.

[paskal]

We would have a better motivation to release more often then:) I propose to keep the current scheme.

[umputun]

I'm planing to keep it as continuous delivery till we done with docs migration and latter on switch to tag-only. It is unclear how users will able to see the current (master) docs in this case, maybe we can just have two site containers, one deployed from the master and one on tags only? For master I can add a site "master.remark42.com" and we can put a reference to README

[paskal]

I vote to keep things on continuous delivery. I'd rather maintain a single set of user documentation and release often rather than have the master and latest versions separately.

[akellbl4]

I don't know any lib that put all of the docs of unreleased features to their documentation.

We shouldn't be adding those since it can be confusing to people.