v2: "help" example does not compile

**Describe the bug**

A compilation error on ec39c45b4f7729bfb2dab5a2062563eae63d4e3d:

```
# command-line-arguments
./main.go:92:3: cannot assign to m.help.Width (neither addressable nor a map index expression)
```

**To Reproduce**
```
cd examples/help
go run main.go
```

**Expected behavior**
It runs.

**Additional context**
Maybe `SetWitdth` method should be used. At least it works for me.
