Discuss versioning of the Science Pipelines

[arunkannawadi]

I didn't see any placeholder section where versioning of the code itself was discussed. Given that we don't follow the (now standard) semantic versioning, it'd be useful to talk about our release cycles and deprecation cycles somewhere.

[timj]

That would be an expansion of section 2 where we do talk about development process and cite my 2018 SPIE paper. Talking about our lack of semantic versioning seems useful.