adjust texinfo category for lzip

[Alfred M. Szmidt]

[second attempt .. bug-lzip and lzip-bug are not the same; Patrice
sorry for the dupe!]

This changes the dircategory to better match what is generally used
for compression tools categories.  Both gzip and bzip2 put it under
"Compression"; and the suggested categorization is the one used by the
Free Software Directory (in some form -
https://directory.fsf.org/wiki/Category/Use/compressing).

2022-01-10  Alfred M. Szmidt  <ams@gnu.org>

        * doc/lzip.texi: Change GNU Texinfo category to "Compression"

--- lzip.texi.~1~       2021-11-29 02:56:06.000000000 +0100
+++ lzip.texi   2022-01-10 11:40:58.342033577 +0100
@@ -9,7 +9,7 @@
 @set UPDATED 29 November 2021
 @set VERSION 1.23-rc1
 
-@dircategory Data Compression
+@dircategory Compression
 @direntry
 * Lzip: (lzip).                 LZMA lossless data compressor
 @end direntry