adding keyboard camera control instructions to viewer (#735)

nerfstudio/viewer/app/src/modules/LandingModal/LandingModal.jsx

@@ -178,6 +178,12 @@ export default function LandingModel(props: LandingModalProps) {
                   .
                 </p>
               </TabPanel>
+              <h3>Camera Keyboard Controls</h3>
+              <p>
+                <div>WASD - horizontal camera translation, QE - vertical camera translation</div> 
+                <div>Arrow Keys - camera rotation</div>
+                <div>Spacebar - reset camera orbit point and view direction to origin</div>
+              </p>
             </div>
           </Typography>
         </Box>