Add type and accepted values information

[plehegar]

Those annotations are intended to be used by validate-repo in the future. It will avoid having to change validate-repo when a new value is added for example for repo-type.

[tripu]

Nice idea! Please see suggestions inline.

Also, I'm wondering if it wouldn't be better to specify the expected types with JSON-LD or JSON Schema syntax, instead of inventing our own.
eg, instead of

number|array<number>

something like this

"anyOf":[{"type":"number"},{"type":"array","items":{"type":"number"}}]

I guess it'll make things easier in validate-repos, if we can use a JSON-LD or JSON Schema library, instead of writing our own parser?

[tripu]

(@plehegar, can you review #55, please?)

[plehegar]

I like the idea of using a schema instead. But that will mean we'll have to integrate a schema validator. Feel to close this pull request without merging.

[tripu]

(Looking at this diff now, because the rebase somehow introduced spurious differences in the PR.)

The reusing-a-syntax thing was a suggestion, @plehegar. Better to merge this as it is than abandon it altogether!

[plehegar]

should be ok to merge now I think.

should be a v.next request

[tripu]

See same inline comment.