Programming Guide: Sequences example (with web actions)

See: https://github.com/apache/incubator-openwhisk-wskdeploy/blob/master/tests/src/integration/websequence/manifest.yaml

```
sequences:
greeting-sequence-1:
actions: greeting-1, greeting-2
web: true
greeting-sequence-2:
actions: greeting-1, greeting-2
web: raw
```

for example, although the actions for "greeting-1" and "greeting-2" may not be declared as web actions, the sequence "greating-sequence-1" produces an action (sequence) that is itself a web action.