added basic usage guide

README.md

@@ -7,7 +7,7 @@ Implementation of [CRYSTALS-Kyber](https://pq-crystals.org/kyber/index.shtml) en
 * [Requirements specification](docs/requirements.md)
 * [Implementation]()
 * [Testing]()
-* [Usage guide]()
+* [Usage guide](docs/usage.md)
 
 ### Weekly reports
 

docs/usage.md

@@ -0,0 +1,41 @@
+# Usage guide
+
+## Installation
+
+Make sure that you have [Poetry](https://python-poetry.org/) installed. After cloning the repository to your computer move to its root directory and run
+
+```
+poetry install
+```
+
+## Usage
+
+Currently `kyber` provides three main functions that can be used directly from Python code. A sample usage is included in  `main.py`.
+
+At the moment there is no GUI or CLI available.
+
+### Tests
+
+Unit tests can be run with
+
+```
+poetry run invoke test
+```
+
+### Coverage
+
+Coverage report can be created with
+
+```
+poetry run invoke coverage-report
+```
+
+after which the report will appear at `htmlcov/index.html`.
+
+### Lint
+
+Run static style cheking with
+
+```
+poetry run invoke lint
+```