Depending on the Kubernetes Setup it might be required to create
additional environment variables - e.g. to allow proxy configurations.

The name `.Values.extraEnv` is similar to what helm stable charts and
the gitlab chart do to allow such modifications.

The value can be used to specify direct variables as well as read
variables from secret or configmaps and thus allows great flexibility.

An example values would look like the following:

```
[…]

extraEnv:
  - name: no_proxy
    value: '100.64.0.0/14,100.68.0.0/16,.cluster.local,.svc'
  - name: HTTPS_PROXY
    valueFrom:
      configMapKeyRef:
        name: proxyout-config
        key: HTTPS_PROXY
```