Spec formats items with multiple types as an array

[richvdh]

Link to problem area:
https://spec.matrix.org/unstable/client-server-api/#_matrixclientv3pushrules_pushcondition

Issue

It is not an array; rather it should be one of string, integer, null or boolean. In other parts of the spec (eg PushRule) we represent this with a | character. (Note that in the case of actions, it is actually an array of strings or objects, so the [] are correct in that case.)

[richvdh]

The source for this definition is here.
Per https://www.openapis.org/blog/2021/02/16/migrating-from-openapi-3-0-to-3-1-0, this "array of types" became valid in OpenAPI 3.1.0.

It looks like we need to update https://github.com/matrix-org/matrix-spec/blob/main/layouts/partials/openapi/render-object-table.html to handle it.

[zecakeh]

This was fixed by #1789.