Flexbox docs

Updated the flexbox documentation for the current flexbox implementation

docs/objects/Flexbox/getFlexShrink.md

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+## getFlexShrink
+
+### Description
+
+The `getFlexShrink` method retrieves the current shrink factor of a child object within the Flexbox container. This value represents how much the object would shrink compared to other objects in the container, in case there isn't enough space.
+
+### Returns
+
+1. `number` The current shrink factor of the object.
+
+### Usage
+
+* Creates a default Flexbox, adds some objects to it, sets the flexShrink for the first object, and retrieves it.
+
+```lua
+local main = basalt.createFrame()
+local flexbox = mainFrame:addFlexbox()
+local object1 = flexbox:addButton()
+object1:setFlexShrink(2) -- this object will shrink twice as much as the others if necessary
+basalt.debug(object1:getFlexShrink()) -- prints: 2
+```