Core/authserver.conf.dist: missing description line (#17038)

This line is missing from authserver.conf.dist :
`#                     MySQL server and their own thread on the MySQL server.`

I have copied this description text line from the matching description in
`worldserver.conf.dist` (line 108 in the 3.3.5 worldserver source file).

This line is also missing in bnetserver.conf.dist , but the files are different
in line number, filename and folder, so bnetserver needs a separate commit.

src/server/authserver/authserver.conf.dist

@@ -179,6 +179,7 @@ LoginDatabaseInfo = "127.0.0.1;3306;trinity;trinity;auth"
 #    LoginDatabase.WorkerThreads
 #        Description: The amount of worker threads spawned to handle asynchronous (delayed) MySQL
 #                     statements. Each worker thread is mirrored with its own connection to the
+#                     MySQL server and their own thread on the MySQL server.
 #        Default:     1
 
 LoginDatabase.WorkerThreads = 1