doc: update timer-db description

doc/man/knot.conf.5in

@@ -484,6 +484,7 @@ if a zone doesn\(aqt have another template specified.
 .ft C
 template:
   \- id: STR
+    timer\-db: STR
     global\-module: STR/STR ...
     # All zone options (excluding \(aqtemplate\(aq item)
 .ft P
@@ -493,12 +494,20 @@ template:
 .SS id
 .sp
 A template identifier.
+.SS timer\-db
+.sp
+Specifies a path of the persistent timer database. The path can be specified
+as a relative path to the \fIdefault\fP template \fI\%storage\fP\&.
+.sp
+\fICaution:\fP This option is only available in the \fIdefault\fP template.
+.sp
+\fIDefault:\fP \fI\%storage\fP/timers
 .SS global\-module
 .sp
 An ordered list of references to query modules in the form
 \fImodule_name/module_id\fP\&. These modules apply to all queries.
 .sp
-\fICaution:\fP This option is available only for the \fIdefault\fP template.
+\fICaution:\fP This option is only available in the \fIdefault\fP template.
 .sp
 \fIDefault:\fP not set
 .SH ZONE SECTION

doc/reference.rst

@@ -552,6 +552,7 @@ if a zone doesn't have another template specified.
 
  template:
    - id: STR
+     timer-db: STR
      global-module: STR/STR ...
      # All zone options (excluding 'template' item)
 
@@ -562,6 +563,18 @@ id
 
 A template identifier.
 
+.. _template_timer-db:
+
+timer-db
+--------
+
+Specifies a path of the persistent timer database. The path can be specified
+as a relative path to the *default* template :ref:`storage<zone_storage>`.
+
+*Caution:* This option is only available in the *default* template.
+
+*Default:* :ref:`storage<zone_storage>`/timers
+
 .. _template_global-module:
 
 global-module
@@ -570,7 +583,7 @@ global-module
 An ordered list of references to query modules in the form
 *module_name/module_id*. These modules apply to all queries.
 
-*Caution:* This option is available only for the *default* template.
+*Caution:* This option is only available in the *default* template.
 
 *Default:* not set