bug#49230: please update description for package nyacc

[Matt Wette]

Hi All,

Could you please remove the "should be considered not stable" language from the 
description of the nyacc package?
The current text on the website (https://www.nongnu.org/nyacc) is the following 
gist:


NYACC, for Not Yet Another Compiler Compiler, is set of guile modules for
generating parsers and lexical analyzers.  It also provides sample parsers,
pretty-printers using SXML trees as an intermediate representation, a decent
C parser and a `FFI Helper' tool to help create Guile Scheme bindings for
C-based libraries.

Thanks,
Matt