Edited Iris Shader: Labelled all group nodes for easier targetting.

[ShinoMythmaker]

• Changed the name and label of the iris.shpk group node to match the name of the node tree.
• Changed the label of Principled BSDF to Principled BSDF.
• Changed the label of UV Map to UV Map (from UVMap).
• Changed the label of Material Output to Material Output.
• Changed the label of Color Attribute to Color Attribute.

This makes it easier to target these nodes

[ShinoMythmaker]

I have also changed the names of the image texture nodes for consistency