bug#13177: 24.3.50; doc of `read-char-by-name'

[Drew Adams]

> >> Dunno just what the intention was for this function.  If it really
> >> was to return a recognized Unicode character then this is a product
> >> bug and reading should not end until the user enters matching input
> >> (or hits `C-g').
>
> > As its docstring says, it also accepts a hexadecimal number
> > of Unicode code whose input can't use completion.
> 
> That does not preclude using require-match.

Yes.

The problem for me is that I don't know what the intention (design) was or why.
Maybe someone has a good reason to return nil or to return a number that does
not correspond to a recognized code point?

The design should be clarified (and perhaps decided/changed, if appropriate)
before we try to fit the doc to it.