Fix uifolder name for subsurface weight (#184)

Subsurface weight has uifolder and uiname values switched.

reference/open_pbr_surface.mtlx

@@ -39,7 +39,7 @@
            doc="Linearly scales the amount of dispersion." />
     <input name="transmission_dispersion_abbe_number" type="float" value="0.0" uimin="0.0" uisoftmin="9.0" uisoftmax="91.0" uiname="Transmission Dispersion Abbe Number" uifolder="Transmission" uiadvanced="true"
            doc="Physical Abbe number of the dielectric medium, describing how much the dielectric index of refraction varies across wavelengths." />
-    <input name="subsurface_weight" type="float" value="0" uimin="0.0" uimax="1.0" uiname="Subsurface" uifolder="Subsurface Weight" uiadvanced="true"
+    <input name="subsurface_weight" type="float" value="0" uimin="0.0" uimax="1.0" uiname="Subsurface Weight" uifolder="Subsurface" uiadvanced="true"
            doc="Mixture weight which dials the opaque dielectric base between diffuse reflection and subsurface scattering. A value of 1.0 indicates full subsurface scattering and a value 0 for diffuse reflection only." />
     <input name="subsurface_color" type="color3" value="0.8, 0.8, 0.8" uimin="0,0,0" uimax="1,1,1" uiname="Subsurface Color" uifolder="Subsurface" uiadvanced="true"
            doc="The observed reflection color of the subsurface scattering medium." />