Updated docs

There is still stuff to do

docs/objects/Slider/setSymbol.md

@@ -0,0 +1,18 @@
+## setSymbol
+Changes the slider symbol, default is " "
+
+#### Parameters: 
+1. `string` symbol
+
+#### Returns:
+1. `object` The object in use
+
+#### Usage:
+* Creates a new slider and changes the symbol to X
+```lua
+local mainFrame = basalt.createFrame()
+local slider = mainFrame:addSlider():setSymbol("X")
+```
+```xml
+<slider symbol="X" />
+```