[doc] Comments in source.

[Teika Kazura <teika lavabit com>]

Hi. 

Janek Kozicki wrote:
> Anyone who understands anything is very much needed to write even a
> small part of the doc. 

Comments in the source, both for C and lisp can also be considered as
a variant of doc. When you modify the source, making a practice
to add a comment, even slightest, helps others to reduce the labor of
understanding the code again. I've given something like:

"This is only called from ..."
"This call should precede xxx, because..."

Use source,
Teika kazura