Docs update

Some more stuff for docs

docs/objects/Object/onLeave.md

@@ -0,0 +1,21 @@
+# onLeave
+
+`onLeave(self, event, button, x, y)`<br>
+The computercraft event which triggers this method is `mouse_move` - only available in [CraftOS-PC](https://www.craftos-pc.cc).
+
+Here is a example on how to add a onLeave event to your button:
+
+```lua
+local basalt = require("basalt")
+
+local main = basalt.createFrame()
+local button = main:addButton()
+  :setPosition(3,3)
+  :setSize(12,3)
+  :setText("Leave")
+
+function buttonOnLeave()
+  basalt.debug("The mouse left the button!")
+end
+button:onLeave(buttonOnLeave)
+```