docs update

Updated some docs stuff

docs/objects/Progressbar/onDone.md

@@ -0,0 +1,19 @@
+# onDone
+
+`onDone(self, err)`<br>
+This is a custom event which gets triggered as soon as the progress is done.
+
+Here is a example on how to add a onDone event to your progressbar:
+
+```lua
+local basalt = require("basalt")
+
+local main = basalt.createFrame()
+local aProgressbar = main:addProgressbar()
+
+local function onProgressDone()
+    basalt.debug("Progress is done")
+end
+
+aProgressbar:onDone(onProgressDone)
+```