guard templates with the if directive where necessary

doc/ikiwiki/directive/template.mdwn

@@ -60,9 +60,14 @@ few things:
   `<TMPL_IF variable>text</TMPL_IF>`.
 * To use one block of text if a variable is set and a second if it's not,
   use `<TMPL_IF variable>text<TMPL_ELSE>other text</TMPL_IF>`
+* Each template file included in the wiki's source will also generate a regular
+  wiki page.  In many cases you might want to prevent some of your template
+  being interpreted for the regular page.  Use the [[if]] directive with the
+  `included()` test to guard the template code.
 
 Here's a sample template:
 
+        \[[!if test="included()" then="""
           <span class="infobox">
           Name: \[[<TMPL_VAR raw_name>]]<br />
           Age: <TMPL_VAR age><br />
@@ -76,6 +81,9 @@ Here's a sample template:
             <TMPL_VAR notes>
           </TMPL_IF>
           </span>
+        """ else="""
+          This is a template page.
+        """]]
 
 The filled out template will be formatted the same as the rest of the page
 that contains it, so you can include WikiLinks and all other forms of wiki