Adding more information in the README to use conversion tool.

examples/convert-llama2c-to-ggml/README.md

@@ -1,13 +1,26 @@
 ## Convert llama2.c model to ggml
 
-This example reads weights from project [llama2.c](https://github.com/karpathy/llama2.c) and saves them in ggml compatible format.
+This example reads weights from project [llama2.c](https://github.com/karpathy/llama2.c) and saves them in ggml compatible format. The vocab that is available in `models/ggml-vocab.bin` is used by default.
 
 To convert the model first download the models from the [llma2.c](https://github.com/karpathy/llama2.c) repository:
 
 `$ make -j`
 
-`$ ./convert-llama2c-to-ggml --vocab-model <ggml-vocab.bin> --llama2c-model <llama2.c model path> --llama2c-output-model <ggml output model path>`
+After successful compilation, following usage options are available:
+```
+usage: ./convert-llama2c-to-ggml [options]
 
-Now you can use the model with command:
+options:
+  -h, --help                       show this help message and exit
+  --copy-vocab-from-model FNAME    model path from which to copy vocab (default 'models/ggml-vocab.bin')
+  --llama2c-model FNAME            [REQUIRED] model path from which to load Karpathy's llama2.c model
+  --llama2c-output-model FNAME     model path to save the converted llama2.c model (default ak_llama_model.bin')
+```
+
+An example command is as follows:
+
+`$ ./convert-llama2c-to-ggml --copy-vocab-from-model <ggml-vocab.bin> --llama2c-model <llama2.c model path> --llama2c-output-model <ggml output model path>`
+
+Now you can use the model with command like:
 
 `$ ./main -m <ggml output model path> -p "One day, Lily met a Shoggoth" -n 500 -c 256 -eps 1e-5`