Help: Clarify that set_target_properties supports multiple targets

Reported-by: Alan W. Irwin <[email protected]>

Help/command/set_target_properties.rst

@@ -9,8 +9,8 @@ Targets can have properties that affect how they are built.
                         PROPERTIES prop1 value1
                         prop2 value2 ...)
 
-Set properties on a target.  The syntax for the command is to list all
-the files you want to change, and then provide the values you want to
+Set properties on targets.  The syntax for the command is to list all
+the targets you want to change, and then provide the values you want to
 set next.  You can use any prop value pair you want and extract it
 later with the :command:`get_property` or :command:`get_target_property`
 command.