updated api xmldocs

com.unity.perception/Runtime/Randomization/Samplers/SamplerUtility.cs

     /// </summary>
     public static class SamplerUtility
     {
-        internal const uint largePrime = 0x202A96CF;
+        /// <summary>
+        /// A large prime number
+        /// </summary>
+        public const uint largePrime = 0x202A96CF;
+
+        /// <summary>
+        /// The number of samples to generate per job batch in an IJobParallelForBatch job
+        /// </summary>
         public const int samplingBatchSize = 64;
 
         /// <summary>

com.unity.perception/Runtime/Randomization/Scenarios/ScenarioConstants.cs

 
 namespace UnityEngine.Experimental.Perception.Randomization.Scenarios
 {
+    /// <summary>
+    /// The base class for implementing custom scenario constants classes
+    /// </summary>
+        /// <summary>
+        /// The starting value initializing all random values sequences generated through Samplers, Parameters, and
+        /// Randomizers attached to a Scenario
+        /// </summary>
         public uint randomSeed = SamplerUtility.largePrime;
     }
 }