Addons: deprecate 'wiki_url'

When running with debug enabled ('-d' argument),
warnings are printed for add-ons which are not yet updated.

Reminder to name things based on what they do,
not the technologies they use :)

release/scripts/templates_py/addon_add_object.py

@@ -6,7 +6,7 @@ bl_info = {
     "location": "View3D > Add > Mesh > New Object",
     "description": "Adds a new Mesh Object",
     "warning": "",
-    "wiki_url": "",
+    "doc_url": "",
     "category": "Add Mesh",
 }