Update Gateway's README ToC with recently added sections
@@ -15,6 +15,9 @@ Information associated with the SignalFx Gateway can be found <a target="_blank"
- [Carbon](#carbon-forwarder)
- [Listeners](#listenfrom)
- [SignalFx](#signalfx-listener)
+ - [Add Tags to Spans](#add-tags-to-spans)
+ - [Identify and Replace variables in Span Names](#identify-and-replace-variables-in-span-names)
+ - [Using AdditionalSpanTags and SpanNameReplacementRules Together](#using-additionalspantags-and-spannamereplacementrules-together)
- [collectd](#collectd-listener)
- [Prometheus](#prometheus-listener)
- [Wavefront](#wavefront-listener)
