Update README.md

Author: rcastley

oteldemo/README.md

@@ -39,6 +39,10 @@ agent:
 
 Using a standard workshop instance install Splunk Otel Collector
 
+``` bash
+helm repo add splunk-otel-collector-chart https://signalfx.github.io/splunk-otel-collector-chart && helm repo update
+```
+
 ``` text
 helm install splunk-otel-collector \
 --set="splunkObservability.realm=$REALM" \