add a brief readme

README.md

+Usage
+=========
+The configuration file controls the network structure, I/O, training setting and hyperparameters. See sltk/SLTKDataUtility.h for more details.
+
+In ***training*** status:
+use 'isTrain: true', 'isSupervised: true'
+If you want to continue the last training, use 'isClean: false'
+
+In ***decoding*** status:
+use 'isTrain: false'
+if you want to evaluate the performance, use 'isSupervised: true'
+else use 'isSupervised: false'
+
+ToDo
+=========
+1. Replace utility functions with functions in library
+2. Optimize code for training and decoding
+3. Add a language model layer to LSTM-CRF networks
+4. Add other components for the model
+5. Evaluate performance on more data set since we have only applied verification on small data sets(2k sentences).
\ No newline at end of file