Doccords for specs/types

[drbeefsupreme]

According to a conversation with @joemfb, I'll want another $hoon tag for spec doccords separate from the %note hoon currently used to wrap hoons. The Hoon 143K iteration of doccords called this tag %halo.

I have an OK idea of what I need to do to make this change, but am not yet sure how it should be prioritized relative to other TODO tasks.

[drbeefsupreme]

This is turning out to be suspiciously easier than I expected. I thought I'd have to add another hoon tag and wire it up inside the compiler, but so far using the %note tag seems to be working fine. Trying to figure out how this might create other issues down the road.

[drbeefsupreme]

@joemfb patiently explained why we should want another hoon and spec tag for specs. If we can get something working quickly, it will go in the first release, otherwise I'll see if there will be any real issues with using the current system just to annotate the +$ arms themselves.

[drbeefsupreme]

@joemfb paired with me to get this working on Wednesday, and it works great. Ex. if you have

+$  tape  (list @tD)     :<  utf8 string as a list

then the type of *tape contains the docs utf8 string as a list. Now I just need to figure out how to print this.