Spec Updated - http-request & vocabulary

I added some editorial text about each vocabulary element and
I expanded the definition of the http-request step and its vocabulary.

-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics