example: add this exporter to the OpenCensus website

[odeke-em]

I just discovered this exporter, great work! I kindly would like to ask if it is possible for anyone working on it to add an example to the website https://github.com/census-instrumentation/opencensus-website

For example this is what the Prometheus exporter information looks like:

• Codelab for setting up Prometheus https://opencensus.io/codelabs/prometheus/#0
• Supported Go exporters https://opencensus.io/guides/exporters/supported-exporters/go/
• Prometheus Go exporter https://opencensus.io/guides/exporters/supported-exporters/go/prometheus/

/cc @Ramonza

If y'all don't have much bandwidth, no worries, I can work on it :)