Feed_contact_email required (#454)

* Feed contact email required

* feed_contact_email Description

* Replace wording (MUST vs SHOULD)

* Clarifying changes 

Add language suggested by @ezmckinn for pointing to generic email rather than individual.

Co-authored-by: Josee Sabourin <[email protected]>

Author: Sergiodero

gbfs.md

@@ -84,7 +84,7 @@ To be compliant with GBFS, all systems MUST have an entry in the [systems.csv](h
 ### Feed Availability
 
 Automated tools for application performance monitoring SHOULD be used to ensure feed availability.
-Producers SHOULD provide a technical contact who can respond to feed outages in the `feed_contact_email` field in the `system_information.json` file.
+Producers MUST provide a technical contact who can respond to feed outages in the `feed_contact_email` field in the `system_information.json` file.
 
 ### Seasonal Shutdowns, Disruptions of Service
 
@@ -355,7 +355,7 @@ Field Name | REQUIRED | Type | Defines
 `start_date` | OPTIONAL | Date | Date that the system began operations.
 `phone_number` <br/>*(as of v3.0-RC)* | OPTIONAL | Phone Number | This OPTIONAL field SHOULD contain a single voice telephone number for the specified system’s customer service department. MUST be in [E.164](https://www.itu.int/rec/T-REC-E.164-201011-I/en) format as defined in [Field Types](#field-types). 
 `email` | OPTIONAL | Email | This OPTIONAL field SHOULD contain a single contact email address actively monitored by the operator’s customer service department. This email address SHOULD be a direct contact point where riders can reach a customer service representative.
-`feed_contact_email` | OPTIONAL | Email | This OPTIONAL field SHOULD contain a single contact email for feed consumers to report technical issues with the feed.
+`feed_contact_email` | Yes | Email | This field MUST contain a single contact email for feed consumers to report issues with the feed. This email address SHOULD point to a stable email address, that does not correspond to an individual but rather the team or company that manages GBFS feeds.
 `timezone` | Yes | Timezone | The time zone where the system is located.
 `license_id` <br/>*(added in v3.0-RC)* | Conditionally REQUIRED | String | REQUIRED if the dataset is provided under a standard license. An identifier for a standard license from the [SPDX License List](https://spdx.org/licenses/). Provide `license_id` rather than `license_url` if the license is included in the SPDX License List. See the GBFS wiki for a [comparison of a subset of standard licenses](data-licenses.md). If the `license_id` and `license_url` fields are blank or omitted, this indicates that the feed is provided under the [Creative Commons Universal Public Domain Dedication](https://creativecommons.org/publicdomain/zero/1.0/legalcode).
 `license_url` | Conditionally REQUIRED <br/>*(as of v3.0-RC)* | URL | REQUIRED if the dataset is provided under a customized license. A fully qualified URL of a page that defines the license terms for the GBFS data for this system. Do not specify a `license_url` if `license_id` is specified. If the `license_id` and `license_url` fields are blank or omitted, this indicates that the feed is provided under the [Creative Commons Universal Public Domain Dedication](https://creativecommons.org/publicdomain/zero/1.0/legalcode). *(as of v3.0-RC)*