doc: massive refactor and simplification to migrate to mkdocs

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

doc/config/logging.md

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+General Logging
+===============
+
+**Syntax:** `log size:200k count:5`
+
+Log rotation for run/task/services using the `log` sub-option with
+redirection to a log file.  Global setting, applies to all services.
+
+The size can be given as bytes, without a specifier, or in `k`, `M`,
+or `G`, e.g. `size:10M`, or `size:3G`.  A value of `size:0` disables
+log rotation.  The default is `200k`.
+
+The count value is recommended to be between 1-5, with a default 5.
+Setting count to 0 means the logfile will be truncated when the MAX
+size limit is reached.
+
+Redirecting Output
+------------------
+
+The `run`, `task`, and `service` stanzas also allow the keyword `log` to
+redirect `stderr` and `stdout` of the application to a file or syslog
+using the native `logit` tool.  This is useful for programs that do not
+support syslog on their own, which is sometimes the case when running
+in the foreground.
+
+The full syntax is:
+
+    log:/path/to/file
+    log:prio:facility.level,tag:ident
+    log:console
+    log:null
+    log
+
+Default `prio` is `daemon.info` and default `tag` is the basename of the
+service or run/task command.
+
+Log rotation is controlled using the global `log` setting.
+
+**Example:**
+
+    service log:prio:user.warn,tag:ntpd /sbin/ntpd pool.ntp.org -- NTP daemon