Updated hosting guidance links

And details about agency_id

Author: schnuerle

policy/README.md

@@ -425,7 +425,7 @@ See [Policy Requirements Examples](/policy/examples/requirements.md) for ideas o
 
 #### Public Hosting
 
-This endpoint is not authenticated (ie. public), and allows the discovery of other public endpoints within Geography, Policy, and Jurisdiction. The agency can host this as a file or dynamic endpoint on their servers, on a third party server, or the OMF can host on behalf of an agency in the [agency program requirements repo](https://github.com/openmobilityfoundation/agency-program-requirements). See this [hosting guidance document](#) for more information.  This requirements file can be [referenced directly](https://github.com/openmobilityfoundation/governance/blob/main/technical/OMF-MDS-Policy-Language-Guidance.md) in an agency's operating permit/policy document when discussing program data requirements, and [updated digitally as needed](#requirement-update-frequency).
+This endpoint is not authenticated (ie. public), and allows the discovery of other public endpoints within Geography, Policy, and Jurisdiction. The agency can host this as a file or dynamic endpoint on their servers, on a third party server, or the OMF can host on behalf of an agency in the [agency program requirements repo](https://github.com/openmobilityfoundation/agency-program-requirements). See this [hosting guidance document](https://github.com/openmobilityfoundation/mobility-data-specification/wiki/Policy-Requirements-OMF-Hosting-Guidance) for more information.  This requirements file can be [referenced directly](https://github.com/openmobilityfoundation/governance/blob/main/technical/OMF-MDS-Policy-Language-Guidance.md) in an agency's operating permit/policy document when discussing program data requirements, and [updated digitally as needed](#requirement-update-frequency). To be compliant with MDS you must obtain an `agency_id` and list your public URL in [agencies.csv](/agencies.csv), per our [guidance document](https://github.com/openmobilityfoundation/mobility-data-specification/wiki/Adding-an-MDS-Agency-ID).
 
 #### Requirement Update Frequency
 
@@ -521,13 +521,13 @@ Contains metadata applicable to the agency and at the top of its [Requirement](#
 | `file_version`               | integer         | Required | Version of this file. Increment 1 with each modification. See [version tracking](#version-tracking) for details. E.g. "3" |
 | `last_updated`               | [timestamp][ts] | Required | When this file `version` was last updated. See [version tracking](#version-tracking) for details. E.g. "1611958740" |
 | `max_update_interval`        | duration        | Required | The expected maximum frequency with which this file could be updated. [ISO 8601 duration](https://en.wikipedia.org/wiki/ISO_8601#Durations). E.g. "P1M" |
-| `agency_id`                  | UUID            | Required | UUID of the agency this file applies to. Must come from [agencies.csv](/agencies.csv) file. E.g. "737a9c62-c0cb-4c93-be43-271d21b784b5" |
+| `agency_id`                  | UUID            | Required | UUID of the agency this file applies to. Must come from [agencies.csv](/agencies.csv) file, per [guidance](https://github.com/openmobilityfoundation/mobility-data-specification/wiki/Adding-an-MDS-Agency-ID). E.g. "737a9c62-c0cb-4c93-be43-271d21b784b5" |
 | `agency_name`                | text            | Required | Name of the agency this file applies to. E.g. "Louisville Metro" |
 | `agency_timezone`            | timezone        | Required | [TZ Database Name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) used for dates and times in Requirements and across all MDS endpoints. E.g. "America/New_York" |
 | `agency_language`            | text            | Required | An [IETF BCP 47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language code, used across all MDS endpoints. E.g. "en-US" |
 | `agency_currency`            | text            | Required | Currency used for all monetary values across all MDS endpoints. E.g. "USD" |
 | `agency_website_url`         | URL             | Required | URL of the agency's general transportation page. E.g. "https://www.cityname.gov/transportation/" |
-| `url`                        | URL             | Required | URL of this file. E.g.  "https://mds.cityname.gov/requirements/1.2.0" |
+| `url`                        | URL             | Required | URL of this file. Must be added to [agencies.csv](/agencies.csv), per [guidance](https://github.com/openmobilityfoundation/mobility-data-specification/wiki/Adding-an-MDS-Agency-ID). E.g.  "https://mds.cityname.gov/requirements/1.2.0" |
 
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