docker-compose build: add error detection or more docs

```
$ docker-compose build
Traceback (most recent call last):
File "/usr/lib/python3.9/site-packages/urllib3/connectionpool.py", line 665, in urlopen
httplib_response = self._make_request(
File "/usr/lib/python3.9/site-packages/urllib3/connectionpool.py", line 387, in _make_request
conn.request(method, url, **httplib_request_kw)
File "/usr/lib64/python3.9/http/client.py", line 1279, in request
self._send_request(method, url, body, headers, encode_chunked)
File "/usr/lib64/python3.9/http/client.py", line 1325, in _send_request
self.endheaders(body, encode_chunked=encode_chunked)
File "/usr/lib64/python3.9/http/client.py", line 1274, in endheaders
self._send_output(message_body, encode_chunked=encode_chunked)
File "/usr/lib64/python3.9/http/client.py", line 1034, in _send_output
self.send(msg)
File "/usr/lib64/python3.9/http/client.py", line 974, in send
self.connect()
File "/usr/lib/python3.9/site-packages/docker/transport/unixconn.py", line 43, in connect
sock.connect(self.unix_socket)
PermissionError: [Errno 13] Permission denied
```

So it is likely that something on my system is not set up properly (like permissions). Cleaner error detection and an error message would be good.