assign med-prescribe maturity of 2

Maturity Level | Maturity title | Requirements
--- | --- | ---
1 | Submitted  | _The above, and …_ Hook definition is written up as a [github pull request](https://github.com/cds-hooks/docs/tree/master/docs/hooks) using the [Hook template](hooks/template/) and community feedback is solicited on the [zulip CDS Hooks stream](https://chat.fhir.org/#narrow/stream/17-cds-hooks).
2 | Tested | _The above, and …_ The hook has been tested and successfully supports interoperability among at least one CDS client and two independent CDS services using semi-realistic data and scenarios (e.g. at a FHIR Connectathon). The github pull request defining the hook is approved and published.
3 | Considered |  _The above, and …_ At least 3 distinct organizations recorded ten distinct implementer comments (including a github issue, tracker item, or comment on the hook definition page), including at least two CDS clients and three independent CDS services. The hook has been tested at two connectathons.

Author: isaacvetter

docs/hooks/medication-prescribe.md

@@ -4,6 +4,7 @@
 | ---- | ----
 | specificationVersion | 1.0
 | hookVersion | 1.0
+| Hook maturity | [2 - Tested](specification/1.0/#hook-maturity-model)
 
 ## Workflow