doc/knotd: document accepted signals

doc/man/knotd.8in

@@ -65,6 +65,11 @@ Print the program help.
 \fB\-V\fP, \fB\-\-version\fP
 Print the program version.
 .UNINDENT
+.SS Signals
+.sp
+If the \fIknotd\fP process receives a SIGHUP signal, it reloads its configuration and
+reopens the log files, if they are configured. Upon receiving a SIGINT signal,
+\fIknotd\fP exits.
 .SH EXIT VALUES
 .sp
 Exit status of 0 means successful operation. Any other exit status indicates

doc/man_knotd.rst

@@ -42,6 +42,13 @@ Parameters
 **-V**, **--version**
   Print the program version.
 
+Signals
+.......
+
+If the `knotd` process receives a SIGHUP signal, it reloads its configuration and
+reopens the log files, if they are configured. Upon receiving a SIGINT signal,
+`knotd` exits.
+
 Exit values
 -----------