feature request: rect support in sequence diagrams

[uriel-sf]

sequenceDiagram
  participant signOut as AuthAPI.logOut
  participant logout as /logout
  participant crossLogoutOrigins

  rect rgb(255, 235, 179)
    signOut->>logout: GET
    logout-->>signOut: crossLogoutOrigins
  end
  rect rgb(252, 192, 192)
    logout->>crossLogoutOrigins: POST: each URL
  end

The VS code mermaid plugin renders the above just fine...