Doc: Document log rotation feature

include "tablename.conf";;

</code>

	<tag><label id="opt-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag>

	Set logging of messages having the given class (either <cf/all/ or

	<cf/{ error|trace [, <m/.../] }/ etc.) into selected destination (a file specified

	as a filename string, syslog with optional name argument, or the stderr

	output). Classes are:

	<tag><label id="opt-log">log "<m/filename/" [<m/limit/ "<m/backup/"] | syslog [name <m/name/] | stderr all|{ <m/list of classes/ }</tag>

	Set logging of messages having the given class (either <cf/all/ or <cf>{

	error|trace [, <m/.../] }</cf> etc.) into selected destination - a file

	specified as a filename string (with optional log rotation information),

	syslog (with optional name argument), or the stderr output.

	Classes are:

	<cf/info/, <cf/warning/, <cf/error/ and <cf/fatal/ for messages about local problems,

	<cf/debug/ for debugging messages,

	<cf/trace/ when you want to know what happens in the network,

	<cf/remote/ for messages about misbehavior of remote machines,

	<cf/auth/ about authentication failures,

	<cf/bug/ for internal BIRD bugs.

	Logging directly to file supports basic log rotation -- there is an

	optional log file limit and a backup filename, when log file reaches the

	limit, the current log file is renamed to the backup filename and a new

	log file is created.

	You may specify more than one <cf/log/ line to establish logging to

	multiple destinations. Default: log everything to the system log, or

	to the debug output if debugging is enabled by <cf/-d//<cf/-D/