yaml: Consider adding a YAML style guide

[nielm]

Consider adding a style guide for YAML files.

Google has a YAML formatter with a certain set of default rules , which I assume expresses the style guide...

https://github.com/google/yamlfmt/blob/main/docs/config-file.md

[vapier]

we don't have a style guide. that formatter is the only thing we have. and even its README is clear:

This tool is not yet officially supported by Google. It is currently maintained solely by @braydonk, and unless something changes primarily in spare time.

[braydonk]

Yes, to be clear the yamlfmt project doesn't make any attempt to lay out an opinionated style. The formatting is done by round-trip-ing yaml through a particular yaml parser in Go, so the default is just however that library decides to format it on output. It wasn't thought out in any way.