Move basically the entire label content inside the item function

Move basically the entire label content, except for the footer, inside
the item function.
This results in a more simplified workflow for generating labels for
different items, since there's just one function call left where the
arguments need to be modified.

label-item.typ

@@ -55,16 +55,18 @@
 
 #import "@preview/cades:0.3.0": qr-code
 
-#let item(itemslug) = [
+#let item(itemname, itemslug, usage) = [
+  == #itemname
   #qr-code("https://wiki.hamburg.ccc.de/item:" + itemslug)
   #text(8pt)[wiki.hamburg.ccc.de/item:#itemslug]
+  === Usage
+  #usage
 ]
 
-== Prusa i3 MK3S
+#item(
-
+  "Prusa i3 MK3s",
-#item("prusa-i3")
+  "prusa-i3",
-
+  // "Introduction required"
-=== Usage
+  "See instructions (in the wiki)"
-//Introduction required
+  // "Freely"
-See instructions (in the wiki)
+)
-//Freely