Restore CHANGELOG

In a recent tidy-up of this repo we lost the CHANGELOG in the root.

I think this is a shame, for two reasons:

1. We lost a visible historical record (“it’s in the git history” doesn’t count as visible) of the evolution of our core IP over the past 8 years
2. We have lost a prominent place to log the ongoing changes we are making to this repo (for example @adatzer’s great work on discoverability via git submodule updates)

I propose:

• Resurrecting the historic CHANGELOG
• Backfilling entries since its deletion
• Adding new entries as we make updates to this repo

For new entries in the CHANGELOG, I would propose simply datestamping them given that they don’t fall under specific release numbers any more (there is no global Snowplow release version at the level of this repo currently - we don’t offer LTS / blessed bundles to OSS yet).

[alexanderdean]

Maybe we put a placeholder at the top of the CHANGELOG explaining what we are planning and linking off elsewhere (/releases?) until such time as we have the more narrative-driven version…

[paulboocock]

We should do this (and automate it) when we automate the updating of the submodules, which we’ve just started working on (cc @adatzer).

I’d suggest introducing a CHANGELOG.json too as this will make autogenerating the CHANGELOG.md far easier and more reliable.