Backgrounding docker otel for prometheus to run

DOC-11764

Author: RichardSmedley

modules/howtos/pages/observability-metrics.adoc

@@ -183,7 +183,7 @@ scrape_configs:
 Now run `opentelemetry-collector` and Prometheus:
 ```
 docker network create shared
-docker run --rm --name otel -v "${PWD}/otel.yaml:/etc/otel-local-config.yaml" -p 4317:4317 -p 10000:10000 --network shared otel/opentelemetry-collector --config /etc/otel-local-config.yaml
+docker run --rm --name otel -v "${PWD}/otel.yaml:/etc/otel-local-config.yaml" -p 4317:4317 -p 10000:10000 --network shared otel/opentelemetry-collector --config /etc/otel-local-config.yaml &
 docker run --rm --name prometheus -p 9090:9090  --mount type=bind,source="${PWD}/prometheus.yaml,destination=/etc/prometheus/prometheus.yml" --network shared prom/prometheus
 ```