bug#25461: [Patch #2]: Missing doc strings for "," and ",@".

[npostavs]

Alan Mackenzie <acm@muc.de> writes:

>
> I've hacked all this together.  What used to be called a "reader macro"
> is now a "reader construct".

I think "read syntax" is better just because the manual already uses
that term.

> +;; Give `,' and `,@' documentation strings which can be examined by C-h f.
> +(put '\, 'function-documentation
> +     "See `\\=`' (also `pcase') for the details of `,'.")
> +(put '\, 'reader-construct t)
> +
> +(put '\,@ 'function-documentation
> +     "See `\\=`' or `,' for the details of `,@'.")

Linking from ",@" to "," seems a bit unhelpful, since "," hardly says
anything and just links to "`".