Updated RM: Added 'Known Issues' section.

README.md

 
 Required: [Unity 2018.1b3](https://unity3d.com/unity/beta/unity2018.1.0b3)
 
+**Known Issues**
+There is sometimes an issue when opening the project for the first time that textures set in the Material Inspector aren't being applied properly; the current 'fix' is to open the related Shader Graph, click the "Save' button and the Material should update. :)
+
 
 **Contact**