[plt-dev] guide vs reference

What is the reason that the guide is separate from the reference? They 
seem close enough to me to warrant merging them.

I have some text to update `parameterize' and it looks like the text 
should go into the guide but I personally almost never read the guide 
and would prefer it in the reference. Separating the guide from the 
reference, even if a good idea logically, only seems to have negative 
practical ramifications. When I go to look up some function in the PLT 
manual I usually end up at the reference and just read that. While its 
true that there are links from the reference to the guide, I usually 
ignore them (ok my fault) but if I'm going to have to read the reference 
and the guide they might as well be the same document.

The first two sections of the guide seem like they don't belong in the 
reference, but every section after 2 has a bit of overlap with the 
reference.