Documentation gaps and inconsistencies (Appendix A markers, README scope, typos) #192

Problem description
Several documentation issues:

• The Appendix A "identifying the device from the access token" text in info.description is
  present but not wrapped in the CAMARA:MANDATORY:identifying-device-from-access-token BEGIN/END
  markers used for the other mandatory blocks in the same file, and has two blank-line differences
  from the Commonalities r4.3 template.
• README ## Scope still lists only retrieve-identifier and retrieve-type; retrieve-ppid (added in
  r2.2) and match-identifier (added this release) are missing.
• No User Story is documented for the new match-identifier endpoint.
• Minor typos / inconsistencies: Permision Denied example key; TAC called "Type Allocation Code" in
  info.description vs "Type Approval Code" in DeviceType.description; "An device identifier"
  description; "subcsription" (x2); "alloacted"; requestBody.description reading "Parameters to
  create a new session" on two operations that don't involve a session; inconsistent OpenAPI
  example-key naming style across response blocks (GENERIC_401_UNAUTHENTICATED vs
  Insufficient Parameters vs Permision Denied); Identifer / folowing typos in three
  feature-file headers.

Expected action
Update info.description to wrap the Appendix A block in its mandatory markers, update the README
Scope section, add a match-identifier user story, and fix the listed typos / naming inconsistencies.

Additional context
Commonalities r4.3 info-description-templates.yaml for the Appendix A marker convention:
https://github.com/camaraproject/Commonalities/blob/r4.3/artifacts/common/info-description-templates.yaml