Add scope, adapted from TF charter (#2)

Author: scouten-adobe

spec/scope.md

@@ -7,4 +7,6 @@
 
 ## Scope
 
-Describe the scope
+The [X.509 VID Task Force](https://wiki.trustoverip.org/pages/viewpage.action?pageId=68453176) (X5VTF) is a task force of the ToIP [Technology Stack Working Group](https://wiki.trustoverip.org/display/HOME/Technology+Stack+Working+Group), which intends to explore how X.509 identifiers can be part of the ToIP verifiable identifier landscape.
+
+The deliverable of this Task Force is the **did:x509 Method Specification** that must meet the requirements of a verifiable identifier (VID) as specified in the [ToIP Technology Architecture V1.0 Specification](https://trustoverip.org/our-work/technical-architecture/) and the draft [ToIP Trust Spanning Protocol Specification](https://wiki.trustoverip.org/display/HOME/ToIP+Trust+Spanning+Protocol+Specification). The requirements in this specification must interoperate with other ToIP component specifications as explained in the [Evolution of the ToIP Stack](https://trustoverip.org/our-work/evolution-of-the-toip-stack/).