tile: remove : in description
tile: remove : in description

resulting tile manifest does not maintain the quoted string and ends up building this invalid YAML:

  - reference: .properties.firehose_events_to_stackdriver_logging
    label: Whitelist for Stackdriver Logging
    description: Comma separated list without spaces consisting of any or all of HttpStartStop,LogMessage,Error. The following events are in beta can also be used: ValueMetric,CounterEvent,ContainerMetric
cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools