Patch jsonschema2rst to make 'doc' render as text

With this MR, doc-text will always render as text rather than monospace-font. We've been working around this by ending all doc-strings with .. It turns out that the period has nothing to do with the period, it's just that any text without a '`' was rendered as code. This patch is specific to DP3's usage of jsonschema2rst, I don't think it makes sense to make a pull-request for the upstream repository.