"Edit>Scene render setting" menu missing in unity 5

Same here, might have been the latest update, using beta 14?

Made a ugly temporary fix for you and anyone else who needs it, me included. Sorry for it being as long as it is, but it works.

Add to "Assets/Editor/MyRenderSettings.cs"

 using UnityEngine;
 using UnityEngine.Rendering;
 using UnityEditor;
 
 [InitializeOnLoad]
 public class MyRenderSettings : EditorWindow
 {
     [MenuItem("Window/Render Settings Temp Fix")]
     static void Init()
     {
         MyRenderSettings renderSettings = (MyRenderSettings)EditorWindow.GetWindow(typeof(MyRenderSettings));
     }
 
     AmbientMode ambientMode
     {
         get { return RenderSettings.ambientMode; }
         set { RenderSettings.ambientMode = value; }
     }
     Color ambientLight
     {
         get { return RenderSettings.ambientLight; }
         set { RenderSettings.ambientLight = value; }
     }
     Color ambientSkyColor
     {
         get { return RenderSettings.ambientSkyColor; }
         set { RenderSettings.ambientSkyColor = value; }
     }
     Color ambientEquatorColor
     {
         get { return RenderSettings.ambientEquatorColor; }
         set { RenderSettings.ambientEquatorColor = value; }
     }
     Color ambientGroundColor
     {
         get { return RenderSettings.ambientGroundColor; }
         set { RenderSettings.ambientGroundColor = value; }
     }
     float ambientSkyboxAmount
     {
         get { return RenderSettings.ambientSkyboxAmount; }
         set { RenderSettings.ambientSkyboxAmount = value; }
     }
     SphericalHarmonicsL2 ambientProbe
     {
         get { return RenderSettings.ambientProbe; }
         set { RenderSettings.ambientProbe = value; }
     }
 
     DefaultReflectionMode defaultReflectionMode
     {
         get { return RenderSettings.defaultReflectionMode; }
         set { RenderSettings.defaultReflectionMode = value; }
     }
     Cubemap customReflection
     {
         get { return RenderSettings.customReflection; }
         set { RenderSettings.customReflection = value; }
     }
 
     float flareFadeSpeed
     {
         get { return RenderSettings.flareFadeSpeed; }
         set { RenderSettings.flareFadeSpeed = value; }
     }
     float flareStrength
     {
         get { return RenderSettings.flareStrength; }
         set { RenderSettings.flareStrength = value; }
     }
 
     bool fog
     {
         get { return RenderSettings.fog; }
         set { RenderSettings.fog = value; }
     }
     FogMode fogMode
     {
         get { return RenderSettings.fogMode; }
         set { RenderSettings.fogMode = value; }
     }
     Color fogColor
     {
         get { return RenderSettings.fogColor; }
         set { RenderSettings.fogColor = value; }
     }
     float fogDensity
     {
         get { return RenderSettings.fogDensity; }
         set { RenderSettings.fogDensity = value; }
     }
     float fogStartDistance
     {
         get { return RenderSettings.fogStartDistance; }
         set { RenderSettings.fogStartDistance = value; }
     }
     float fogEndDistance
     {
         get { return RenderSettings.fogEndDistance; }
         set { RenderSettings.fogEndDistance = value; }
     }
 
     float haloStrength
     {
         get { return RenderSettings.haloStrength; }
         set { RenderSettings.haloStrength = value; }
     }
     Material skybox
     {
         get { return RenderSettings.skybox; }
         set { RenderSettings.skybox = value; }
     }
 
     void OnGUI()
     {
         GUILayout.Label("Ambient and skybox", EditorStyles.boldLabel);
         ambientMode = (AmbientMode)EditorGUILayout.EnumPopup("Ambient Mode", ambientMode);
         ambientLight = EditorGUILayout.ColorField("Ambient Light Color", ambientLight);
         ambientSkyColor = EditorGUILayout.ColorField("Ambient Sky Color", ambientSkyColor);
         ambientEquatorColor = EditorGUILayout.ColorField("Ambient Equator Color", ambientEquatorColor);
         ambientGroundColor = EditorGUILayout.ColorField("Ambient Ground Color", ambientGroundColor);
         ambientSkyboxAmount = EditorGUILayout.FloatField("Ambient Skybox Amount", ambientSkyboxAmount);
         //ambientProbe = (SphericalHarmonicsL2)EditorGUILayout.ObjectField(ambientProbe, typeof(SphericalHarmonicsL2), true);   //Doesnt seem t0o work, skipped this
         haloStrength = EditorGUILayout.FloatField("Halo Strength", haloStrength);
         skybox = (Material)EditorGUILayout.ObjectField("Skybox", skybox, typeof(Material), true);
 
         GUILayout.Label("Reflection", EditorStyles.boldLabel);
         defaultReflectionMode = (DefaultReflectionMode)EditorGUILayout.EnumPopup("Default Reflection Mode", defaultReflectionMode);
         customReflection = (Cubemap)EditorGUILayout.ObjectField("Custom Reflection", customReflection, typeof(Cubemap), true);
 
         GUILayout.Label("Flare", EditorStyles.boldLabel);
         flareFadeSpeed = EditorGUILayout.FloatField("Flare Fade Speed", flareFadeSpeed);
         flareStrength = EditorGUILayout.FloatField("Flare Strength", flareStrength);
 
         GUILayout.Label("Fog", EditorStyles.boldLabel);
         fog = EditorGUILayout.Toggle("Fog enabled", fog);
         fogMode = (FogMode)EditorGUILayout.EnumPopup("Fog Mode", fogMode);
         fogColor = EditorGUILayout.ColorField("Fog Color", fogColor);
         fogDensity = EditorGUILayout.FloatField("Fog Density", fogDensity);
         fogStartDistance = EditorGUILayout.FloatField("Fog Start Distance", fogStartDistance);
         fogEndDistance = EditorGUILayout.FloatField("Fog End Distance", fogEndDistance);
     }
 }