brotli: Update the Internet-Draft link and package description (#429684)

pkgs/by-name/br/brotli/package.nix

···
 
   meta = with lib; {
     homepage = "https://github.com/google/brotli";
-    description = "Generic-purpose lossless compression algorithm and tool";
+    description = "General-purpose lossless compression library with CLI";
     longDescription = ''
       Brotli is a generic-purpose lossless compression algorithm that
       compresses data using a combination of a modern variant of the LZ77
···
       deflate but offers more dense compression.
 
       The specification of the Brotli Compressed Data Format is defined
-      in the following internet draft:
-      http://www.ietf.org/id/draft-alakuijala-brotli
+      in the following Internet-Draft:
+      https://datatracker.ietf.org/doc/html/rfc7932
     '';
     license = licenses.mit;
     maintainers = with maintainers; [ freezeboy ];