message: security: add IBM to distributors, clarify policy.
diff: @@ -329,7 +329,8 @@ customers, of which approximately 400 are using Seven in production. [links]
  We announce on our blog all upstream patches we apply to "Seven." [link to blog
  posts]
  -> 4. Not be a downstream or rebuild of another distribution.
  +> 4. Not be a downstream or rebuild of another distribution. If you offer Envoy as a publicly
  +> available infrastructure or platform service, this condition does not need to apply.
  This does not apply, "Seven" is a unique snowflake distribution.
  @@ -376,6 +377,7 @@ CrashOverride will vouch for the "Seven" distribution joining the distribution l
  | vulnerabilityreports@cloudfoundry.org | Cloud Foundry |
  | secalert@datawire.io | Datawire |
  | google-internal-envoy-security@google.com | Google |
  +| argoprod@us.ibm.com | IBM |
  | vulnerabilities@discuss.istio.io | Istio |
  | secalert@redhat.com | Red Hat |
  | envoy-security@solo.io | solo.io |
  