Write git message format/etiquette guide

[RandomSpaceship]

Having the Git messages in a (mostly) standard format makes it significantly easier to see what's changed at a glance.

[RandomSpaceship]

Thoughts:

Format: package or package(node), preferring, in order:

• package(node): sensors(m2m2_lidar)
• language(specification): nix(flake)
• docs(section): docs(architecture)
• chore

Each commit should be a small logical block, which always leaves the code in a working state.

[DingoOz]

+1 for calling this "gitiquette" or "commitiquette" :)

[DingoOz]

Point of style, should the comments after the colon start with a capital letter or lower case?

[RandomSpaceship]

I don't really mind either way, but it probably should be uppercase if we're formalizing it.