Document how spec and code changes are released

[vladimir-v-diaz]

Description of issue or feature request:

The ROADMAP doesn't adequately cover or explain how changes are introduced to the spec and codebase. For instance, how are backwards-incompatible changes released? Are there stable, alpha, beta releases? Which branch contains the latest changes and design?

[vladimir-v-diaz]

The release schedule can also be captured via TAPs, similar to Python's informational PEPs (e.g., PEP 569 and 373).

Informational TAPs on releases was requested by @trishankatdatadog. Thanks!

[trishankatdatadog]

Thank you, sir!

[joshuagl]

There's a WIP TAP to address how spec changes are released theupdateframework/taps#107

[MVrachev]

If this TAP theupdateframework/taps#107 is merged do we need that issue, yet?

[mnm678]

I believe that TAP and the release process both document this issue. I will close this issue, feel free to reopen if this is still a concern.