Add documentation for creating a fork (#447)

Author: joshleecreates

README.md

@@ -163,6 +163,8 @@ In case you need to run a specific suite of tests you can execute
 - [Lightstep](https://github.com/lightstep/opentelemetry-demo)
 - [New Relic](https://github.com/newrelic/opentelemetry-demo)
 
+See [Forking](./docs/forking.md) for more information about creating your own fork.
+
 ## Contributing
 
 See [CONTRIBUTING.md](CONTRIBUTING.md)

docs/forking.md

@@ -0,0 +1,76 @@
+# Forking this Repository
+
+This repository is designed to be forked and used as a tool to show off what you
+are doing with OpenTelemetry.
+
+Setting up a fork or a demo usually only requires overriding some environment
+variables and possibly replacing some container images.
+
+Live demos can be added to the [README](https://github.com/open-telemetry/opentelemetry-demo/blob/main/README.md?plain=1#L186)
+
+## Building Custom Images
+
+Docker Compose uses  `IMAGE_VERSION`  and `IMAGE_NAME` from `.env`  to tag all
+images. Modify these values in order to push or pull custom images from your
+container registry of choice.
+
+## Configuring the Collector
+
+The collector is configured to export traces to jaeger and metrics to prometheus
+in
+[otelcol-config.yml](https://github.com/open-telemetry/opentelemetry-demo/blob/main/src/otelcollector/otelcol-config.yml)
+
+You may wish to make a copy of
+[otelcol-config-extras.yml](https://github.com/open-telemetry/opentelemetry-demo/blob/main/src/otelcollector/otelcol-config-extras.yml)
+for your fork and to modify the relevant volume mounts for the collector in
+[docker-compose.yaml](https://github.com/open-telemetry/opentelemetry-demo/blob/main/docker-compose.yml)
+
+## Configuring the Collector [Helm/Kubernetes]
+
+The [helm
+charts](https://github.com/open-telemetry/opentelemetry-helm-charts/tree/main/charts/opentelemetry-demo)
+allow for easy customization of collector configuration using a custom values
+file:
+
+```yaml
+opentelemetry-collector:
+  config:
+    exporters:
+      otlp:
+        endpoint: "your-otlp-endpoint.com:4317"
+        headers:
+          "x-vendor-api-key": "YOUR_API_KEY"
+    service:
+      pipelines:
+        metrics:
+          exporters:
+            - otlp
+        traces:
+          exporters:
+            - otlp
+            - jaeger
+```
+
+Save this file and pass it into helm:
+
+```shell
+helm install opentelemetry-demo
+open-telemetry/opentelemetry-demo --values opentelemetry-demo-values.yaml
+```
+
+Values provided in this way will be merged with the default values.
+
+## Image Overrides [Helm/Kubernetes]
+
+Each service has a key `imageOverride` which accepts a map of image override
+options, for example:
+
+```yaml
+components:
+  adService:
+    imageOverride:
+      repository: "my-repo"
+      tag: "my-tag"
+      pullSecrets: {}
+      pullPolicy: Always
+```