multi: move logcompressor to logging.file.compressor

This is not a breaking change since the logcompressor config option has
not been released yet.

sample-lnd.conf

@@ -36,9 +36,6 @@
 ; Max log file size in MB before it is rotated.
 ; maxlogfilesize=10
 
-; Compression algorithm to use when rotating logs.
-; logcompressor=gzip
-
 ; Time after which an RPCAcceptor will time out and return false if
 ; it hasn't yet received a response.
 ; acceptortimeout=15s
@@ -988,6 +985,12 @@
 ; Disable logging to the standard LND log file.
 ; logging.file.disable=false
 
+; Compression algorithm to use when rotating logs.
+; Default:
+;   logging.file.compressor=gzip
+; Example:
+;   logging.file.compressor=zstd
+
 ; Don't add timestamps to logs written to the standard LND log file.
 ; logging.file.no-timestamps=false