Add Documentation on Outlines Versioning and Releases

[lapp0]

Problem

We want to ensure downstream users are aware of Outlines versioning scheme and how to safely depend on and pin Outlines.

Solution

Create a documentation page

Rendered: https://github.com/lapp0/outlines/blob/versioning-docs/docs/versioning.md

[rlouf]

Great! We need to link this from somewhere, for instance the Community menu.