Update README.md

Author: Jungjee

README.md

@@ -1,2 +1,13 @@
 # a_dcf
 a-DCF: an architecture agnostic metric
+
+## Installation
+- We support package installation via PyPi. For Python users, `pip install a_dcf` will install the package.
+- Alternatively, installation of this repo is also available via `python -m pip install -e .`
+
+## Usage
+- With default a-DCF configuration (a-DCF1 in the paper)
+```
+from a_dcf import calculate_a_dcf
+results = calculate_a_dcf(YOUR_SCORE_FILE_DIR)
+```