Update README.md

Merge pull request #58 from AnomalousUnderdog/Improvements

Fixed undo for Spline and SplineExtrusion

Selecting an Extrusion Segment will now select the Spline instead

fix: some generated object where not cleaned correctly

packages + settings

splines are now visible whenever they are in the selection hierarchy

selected node is now drawn in a more compact way

Node list is now readonly (and using serialized prop)

static colors are now static

added support for spline object rotation during node drag

removed experimental mention

removed adding node by draging another with alt pressed

cleaning

SplineMeshTiling does not generate content in the prefab editor anymore