added code credit to shadow HLSL files

Assets/Shaders/Shadows/ShaderGraphs/BlurredShadowPlaneLighting.hlsl

+// Code written by Landon Townsend
+
 void MainLightBlurShadow_half(half rand, half fadeTightness, SamplerState pointClamp, half blurRadius, half3 worldPos, out half shadowAtten)
 {
 #if SHADERGRAPH_PREVIEW

Assets/Shaders/Shadows/ShaderGraphs/PlaneContactShadows.hlsl

+// Code written by Landon Townsend
+
 void PlaneContactShadow_float(float rand, float3 position, float dist, float depth, out float shadowAmount)
 {
 #if SHADERGRAPH_PREVIEW