Added test command and improved type hint rule

CONTRIBUTING.md

@@ -15,7 +15,10 @@ Once your request is accepted, you can start your local development.
 2. Make the changes needed and write accompanying tests.
 3. Check if the code written follows the styling guide below.
 4. Run the finished version, using python 3.7, to check if you've made any errors.
-5. Run the tests.
+5. Run the tests (unittest is used). This can be done with a button click within VS Code, or with the following command where you need to be inside the root folder of the project:
+```bash
+python3 -m unittest discover -v -s './tests' -p '*_test.py'
+```
 6. Test your version thoroughly to catch as many bugs as possible (if any).
 
 ## Styling guide
@@ -23,7 +26,7 @@ The code of Noted is written in such way that it follows the following rules. Yo
 
 1. Compatible with python 3.7 .
 2. Tabs (4 space size) are used for indentation.
-3. Type hints are used as much as possible, avoiding importing functions or classes from other files _just_ for the type hinting.
+3. Use type hints as much as possible, though don't if it requires importing extra functions or classes (except for the `typing` library).
 4. Each function in the backend needs a doc string describing the function, what the inputs are, what errors could be raised from within the function and what the output is.
 5. Each function in the `api.py` file should have a doc string describing the api endpoint. For the formatting, look at the doc strings of the other functions in the file.
 6. The imports need to be sorted (the extension `isort` is used in VS Code).