DRTVWR-559: Cleanup: Preserve note about legacy dist_atten magic number

indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl

@@ -52,6 +52,9 @@ float calcLegacyDistanceAttenuation(float distance, float falloff)
 {
     float dist_atten = 1.0 - clamp((distance + falloff)/(1.0 + falloff), 0.0, 1.0);
     dist_atten *= dist_atten;
+
+    // Tweak falloff slightly to match pre-EEP attenuation
+    // NOTE: this magic number also shows up in a great many other places, search for dist_atten *= to audit
     dist_atten *= 2.0;
     return dist_atten;
 }