Specify versioning scheme in Ooni Release-Procedure.md

The current release procedure for Ooni would benefit from describing the versioning scheme. This should serve two purposes:

users can make decisions about installation and upgrade. For example, they may choose to not install a new release if they prefer to only upgrade to security fixes or "stable" releases.
if a new Ooni dev comes along and makes a new release, they will not violate the expectations of users.

Keep in mind there are at least two categories of "user": probe operators and backend service providers.

As a bonus, the versioning scheme should also be described in each package's own documentation, or perhaps those docs should link to a single source of truth in the spec repository.

Trac:
Username: nathan-at-least

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