add instructions about model loading

README.md

@@ -21,6 +21,10 @@ For the docker build, you will just need docker in order to build and run the co
 * git
 * libosmesa6-dev (for open3d headless rendering)
 
+**BEFORE BUILDING** as of writing, you will need to copy the model file manually to `.data/models/motion_state_pred_opdformerp_rgb.pth`
+in the repository. This step must occur before the docker build, or if building locally then before running. Future
+work will make this step no longer required.
+
 ### Docker (preferred)
 
 To build the docker container, run