Verify all ports are free (#983)

* Verify all ports are free

Found out I had some in use ports, this might be helpful to
others starting out as well.

Extracted the needed ports from docker-compose.yml using:

```
yq -r '.services[]?.ports[]? // empty' docker-compose.yml | \
  grep ':' | \
  sed -E 's/^"?([0-9]+):[0-9]+.*"?$/\1/' | \
  sort -n | uniq
```

* Apply suggestions from code review

Co-authored-by: kvdb <[email protected]>

---------

Co-authored-by: Mark Moes <[email protected]>
Co-authored-by: kvdb <[email protected]>

Author: 3 people

docs/workshops/advanced/bootstrap.md

@@ -90,6 +90,17 @@ COMPOSE_PROFILES=lso docker compose up
 This will also enable LSO, so network devices will be actually configured. If you don't want this, just use:
 
 ### Local environment
+
+The environment requires several ports to be free.
+Use either command below to check if any are in use. No output means they're available:
+
+```
+netstat -tulnp | grep -E ':80|:3000|:4000|:5432|:5678|:8000|:8001|:8080'
+ss -tulnp|grep -E ':80|:3000|:4000|:5432|:5678|:8000|:8001|:8080'
+```
+
+Start the containers:
+
 ```
 docker compose up -d
 ```