added development notes to Readme.md

Readme.md

@@ -15,7 +15,11 @@ Python client for the Porkbun API
 3. [Usage](#usage)
 4. [Notes](#notes)
 5. [Third party notices](#third-party-notices)
-6. [License](#license)
+6. [Development](#development)
+    1. [Setup environment](#setup-environment)
+    2. [Tests](#tests)
+    3. [Documentation](#documentation)
+7. [License](#license)
 
 ---
 
@@ -146,6 +150,44 @@ and [PePy](https://github.com/psincraian/pepy). The tests use [ipify](https://gi
 
 _This project is not associated with Porkbun LLC._
 
+### Development
+
+#### Setup environment
+
+First get the source code:
+
+```commandline
+git clone https://github.com/infinityofspace/pkb_client.git
+cd pkb_client
+```
+
+Now create a virtual environment, activate it and install all dependencies with the following commands:
+
+```commandline
+python3 -m venv venv
+source venv/bin/activate
+pip3 install -r requirements.txt
+```
+
+Now you can start developing.
+
+#### Tests
+
+You can run the tests with the following command:
+
+```commandline
+python -m unittest tests/*.py
+```
+
+#### Documentation
+
+To build the documentation you can use the following commands:
+
+```commandline
+sphinx-apidoc -f -o docs/source pkb_client
+cd docs && make html
+```
+
 ### License
 
 [MIT](https://github.com/infinityofspace/pkb_client/blob/master/License) - Copyright (c) Marvin Heptner