Update Keras README with compile option

hpvm/projects/keras/README.md

@@ -68,7 +68,7 @@ List of benchmarks and the expected accuracies:
 ### Synopsis
 
 ```
-python src/${BENCH_NAME}.py  [hpvm_reload|keras_reload]  [frontend] 
+python src/${BENCH_NAME}.py  [hpvm_reload|keras_reload]  [frontend] [compile]
 
 ```
 
@@ -81,6 +81,12 @@ python src/${BENCH_NAME}.py  [hpvm_reload|keras_reload]  [frontend]
 
 `frontend`: Invokes the HPVM frontend and dumps weights (in HPVM `.bin` format) in the output directory specified. The parameters that control where data and source files are dumped are specified by parameters `data_dir` and `src_dir`, respectively. These are described below.
 
+`compile`: Optional Parameter. When specified, it compiles the HPVM-C code generated by the frontend into an HPVM binary under the directory specified by `src_dir` (described below). If `src_dir` path exists, a unique directory (which appends a unique ID) is created. 
+The binary is built with the name `HPVM_binary`. 
+
+**NOTE:** Before running `HPVM_binary` necessary to set CUDA/CUDNN paths with:
+
+`source ${HPVM_root}/set_paths.sh`
 
 **Parameters to Change in Code**