code: func IsConfigBlock(block *cb.Block) bool {
  	envelope, err := ExtractEnvelope(block, 0)
  	if err != nil {
  		return false
  	}
  
  	payload, err := GetPayload(envelope)
  	if err != nil {
  		return false
  	}
  
  	if payload.Header == nil {
  		return false
  	}
  
  	hdr, err := UnmarshalChannelHeader(payload.Header.ChannelHeader)
  	if err != nil {
  		return false
  	}
  
  	return cb.HeaderType(hdr.Type) == cb.HeaderType_CONFIG || cb.HeaderType(hdr.Type) == cb.HeaderType_ORDERER_TRANSACTION
  }
docs: // IsConfigBlock validates whenever given block contains configuration
  // update transaction