[master] Updated ChangeLog entry for #2315.

The updated description specifies that the change was in the DHCP code.
Also, the updated entry points out that new code is used internally by
the DHCP server. Okayed on jabber.

ChangeLog

 541.	[func]		marcin
-	Added routines to search for configured options and their
+	Added routines to search for configured DHCP options and their
 	definitions using name of the option space they belong to.
+	New routines are called internally from the DHCPv4 and DHCPv6
+	servers code.
 	(Trac #2315, git 741fe7bc96c70df35d9a79016b0aa1488e9b3ac8)
 
 540.	[func]		marcin