Contradictory documentation of keys in /search API

The documentation for `keys` for the type "Room Events Criteria" under [the `/search` API](https://matrix.org/docs/spec/client_server/r0.4.0.html#post-matrix-client-r0-search) says this:

> The keys to search. Defaults to all. One of: `["content.body", "content.name", "content.topic"]`

However, the type of the property is `[enum]` (array) and the example is also an array containing one of the enum values.

Is it true that only one of the enum values can be supplied? And if so, why is it an array?

Read the linked `/search` API section and the definition of the “Room Events Criteria” type. Determine whether `keys` accepts one or multiple enum values, then update the documentation so the prose, array type, and example agree; done means the contradiction is removed.

Written by the indexing model from the issue text.