Improving documentation

[dsixdkt]

Hi,

In the tzatziki-http module documentation, there is a reference to the templating capacity, somewhat explaining how to use external vairables in payload.

But what I was trying to do, is saving data from request response in the context to reuse it later.
I finally come out with this, really not obvious, syntaxe to do it.

And dktToken is:
    """yml
    {{{[_response.body.payload.name]}}}
    """

Though it seams possible to use just this syntaxe _response.body.payload.name (in plain text with out any decoration) when it is on the left side of an expression.

Is it possible to add a section in the doc to explain when we should use {{maVar}} or {{{maVar}}} or {{{[maVar]}}} ?

And in the README, there are no example for this use case. It could be worth adding it in my opinion. What do you think?