docs: getting started

This also adds horizontal scrollbar to `<code>` if necessary

For review:

- `grunt`,
- goto `localhost:8000/start`

I largely used one of David's plunks and Paweł's repo https://github.com/PK1A/hsp-hello-gulp  for code samples.

In the example I had to resort to `klass` and `attributes` so that I can really have a parameter in template that is actually passed further to the controller. 

Paweł's sample is much simpler though the parameter passed in [1] is actually discarded and the init value has to be hardcoded in [2].

[1] https://github.com/PK1A/hsp-hello-gulp/blob/master/src/index.html#L8
[2] https://github.com/PK1A/hsp-hello-gulp/blob/master/src/hello.js#L2