Patch to add documentation for spec files

[Nick Clifton]

Hi Richard,

: > + @item %P
: > + Like @samp{%p}, but puts @samp{__} before and after the name of each macro.
: > + (Except macros that already have @samp{__}).
: > + This is for ANSI C. 
: 
: I think it would be better to rewrite the whole parenthetical sentence 
: without the parentheses.  The specification of what happens here is 
: incorrect according to the code further down.  The rule in the source code 
: is
: 
:       if (*y != '_'
:           || (*(y+1) != '_'
:               && ! ISUPPER ((unsigned char)*(y+1))))
: 
: And we only check the start of the keyword (we don't stick __ on the end 
: if it was missing, so __foo and _Foo are not changed).
: 
: I also think it should be clarified here that this is only done to 
: pre-defined macros.

How about this text:

     Like `%p', but puts `__' before and after the name of each
     predefined macro, except for macros that start with `__' or with
     `_L', where L is an uppercase letter.  This is for ANSI C.

Cheers
	Nick