man: update description of logging

Fixes #2762.

man/common-options.inc

@@ -2,9 +2,8 @@
 
 ** -d, --debug
 Makes *mu* generate extra debug information, useful for debugging the program
-itself. By default, debug information goes to the log file, _~/.cache/mu/mu.log_.
-It can safely be deleted when *mu* is not running. When running with *--debug*
-option, the log file can grow rather quickly. See the note on logging below.
+itself. Debug information goes to the standard logging location; see
+{{{man-link(mu,1)}}}.
 
 ** -q, --quiet
 Causes *mu* not to output informational messages and progress information to
@@ -14,7 +13,7 @@ recommended you use this option when using *mu* from scripts etc.
 
 ** --log-stderr
 Causes *mu* to not output log messages to standard error, in addition to sending
-them to the log file.
+them to the standard logging location.
 
 ** --nocolor
 Do not use ANSI colors. The environment variable *NO_COLOR* can be used as an

man/mu.1.org

@@ -79,6 +79,17 @@ The *index*, *find*, and *cfind* commands work with the database, while the othe
 ones work on individual mail files. Hence, running *view*, *mkdir* and *extract* does
 not require the *mu* database.
 
+* LOGGING
+
+*mu* logs to the standard logging location, which is either the systemd journal,
+*syslog* or a log file (by default, _~/.cache/mu/mu.log_), depending on your
+*system's setup; the first that appears to be working is used.
+
+When using a log file, it can safely be deleted when *mu* is not running. When
+running with *--debug* option, the log file can grow rather quickly. See the note
+on logging below.
+
+
 #+include: "common-options.inc" :minlevel 1
 
 #+include: "exit-code.inc" :minlevel 1