tutorial: Fix description of sitemap 'type'

In the tutorial, the generic sitemap description says that ItemType has
to be the same as the type defined in default.items.
Looking at
https://www.openhab.org/docs/configuration/items.html#type and
https://www.openhab.org/docs/configuration/sitemaps.html#element-types
this is incorrect as they take different values.
The example is even mislading as `Switch` is one of the only types which
is common between items and sitemaps. Might be better to describe
`Default` instead.

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>

tutorials/beginner/sitemap.md

@@ -107,10 +107,12 @@ Next comes the block with the actual items you want to show on your sitemap. Her
 The syntax is again pretty straight:
 
 ```bash
-ItemType item=ItemName label="Description of the item shown on the webpage"
+ElementType item=ItemName label="Description of the item shown on the webpage"
 ```
 
-where ItemType and ItemName must be the same as defined in default.items
+where ItemName must be the same as defined in default.items
+
+You can find a detailed overview of the different element types [here]({{base}}/configuration/configuration/sitemaps.html#element-types)
 
 One last thing to do is setting the default sitemap for the "Basic UI" via "Paper UI".
 Browse to "Configuration -> Services" in Paper UI and click the "Configure" button of Basic UI