bug#8693: 24.0.50; doc strings in syntax.el

[Drew Adams]

> >> Need descriptions of what EXP and EXPs are: meanings and possible
> >> values (types).
> 
> I think the natural interpretation here is that EXP is of the same type
> as SYNTAX otherwise described.  (And EXPS is a list of whatever that is.)

There is no "natural interpretation".  Such things need to be
specified.  If Emacs Dev knows what the meaning/behavior is
then it should specify it.  If it does not know then it should
not expect users to guess.

> >> 6. Doc string of `syntax-ppss-cache': Describe POS and PPSS.
> >> 7. Doc string of `syntax-ppss-last': Describe LAST-POS and LAST-PPSS.
> 
> Seems unnecessary for these internal things.

They are not internal.  Programmers who use these functions
deserve to know what their parameters are.  This is why we
have doc strings.