Update documentation.

Refs #5846

doc/4.1-configuration-syntax.md

@@ -24,8 +24,8 @@ define objects the `object` keyword is used:
 
 Each object is uniquely identified by its type (`Host`) and name
 (`host1.example.org`). Objects can contain a comma-separated list of
-property declarations. The following data types are available for
-property values:
+property declarations. Instead of commas semi-colons may also be used.
+The following data types are available for property values:
 
 ### Expressions
 
@@ -52,6 +52,9 @@ Example:
 Supported suffixes include ms (milliseconds), s (seconds), m (minutes),
 h (hours) and d (days).
 
+Duration literals are converted to seconds by the config parser and
+are treated like numeric literals.
+
 #### <a id="string-literals"></a> String Literals
 
 A string.
@@ -170,7 +173,7 @@ in       | "foo" in [ "foo", "bar" ] (true)              | Element contained in
 !in      | "foo" !in [ "bar", "baz" ] (true)             | Element not contained in array
 ()       | (3 + 3) * 5                                   | Groups sub-expressions
 
-Constants may be used in constant expressions:
+Constants may be used in expressions:
 
     const MyCheckInterval = 10m
 
@@ -200,7 +203,7 @@ intersection(array, array, ...) | Returns an array containing all unique element
 string(value)                   | Converts the value to a string.
 number(value)                   | Converts the value to a number.
 bool(value)                     | Converts to value to a bool.
-log(string)                     | Writes a message to the log.
+log(value)                      | Writes a message to the log. Non-string values are converted to a JSON string.
 
 ### <a id="operators"></a> Dictionary Operators
 
@@ -353,13 +356,11 @@ override its value by setting it explicitely to `null`.
       custom = null
     }
 
-
 The same method applies for disabling services defined in the inline `services`
 dictionary by explicitly overriding their value with `null`.
 
     services["ping6"] = null
 
-
 ### <a id="constants"></a> Constants
 
 Global constants can be set using the `const` keyword: