Better documentation: describe usage in template

[PetrDlouhy]

I spent few hour figuring out, why inline formsets doesn't work. The cause was that I used {{ form }} instead of {{ formset }} in template. I didn't find any mention about this in the docs. This is worth of describing somewhere.

[PetrDlouhy]

The usage for WithInlinesViews is even more tricky. I wouldn't have a chance to guess it without the example in tests:

{{ form }}

{% for formset in inlines %}

{{ formset }}

{% endfor %}

[sdolemelipone]

Addressed in #178.