Updated README from examples

examples/README.md

@@ -6,9 +6,22 @@ cd build
 cmake ..
 make
 cd ..
+```
 
+#### Running
+```
 chmod +x *.sh
-
 ./run_demo.sh
 ./run_demo2.sh
 ```
+or
+```
+# using a web camera
+./build/bgs_demo
+
+# using a video file
+./build/bgs_demo ../dataset/video.avi
+
+# using a sequence of images
+./build/bgs_demo2 ../dataset/frames
+```