Query string params that can be defined multiple times should be represented differently

`[string]` is only so helpful when the server is supposed to expect `?ver=1&ver=2`

The issue names no file or test; start by locating the Matrix specification section that defines query-string parameters and reviewing how repeated parameters are currently represented. Done means the specification gives an unambiguous representation for parameters such as ?ver=1&ver=2, with consistent surrounding guidance.

Written by the indexing model from the issue text.