Add mac dev guide

DEVELOPMENT.md

@@ -34,4 +34,44 @@ You should have docker installed in your system, if not click [here](https://doc
     docker exec diagrams ./autogen.sh
     ```
 
-6. If the unit tests and the bash script `autogen.sh` is working correctly, then your system is now ready for development.
+6. If the unit tests and the bash script `autogen.sh` is working correctly, then your system is now ready for development.
+
+
+## Mac local development setup
+
+To be able to develop and run diagrams locally on you Mac device, you should have [Python](https://www.python.org/downloads/), [Go](https://golang.org/doc/install) and [brew](https://brew.sh/) installed on your system.
+
+1. Go to diagrams root directory.
+
+2. Install poetry, the Python project management packge used by diagrams.
+
+    ```shell
+    pip install poetry
+    ```
+
+3. Install the project's Python dependencies.
+
+    ```shell
+    poetry install
+    ```
+
+4. Install diagrams binary dependencies.
+
+    ```shell
+    brew install imagemagick inkscape black
+    go get github.com/mingrammer/round
+    ```
+
+5. Run unit tests to confirm that it's working.
+
+    ```shell
+    python -m unittest tests/*.py -v
+    ```
+
+6. Run the bash script `autogen.sh` to test.
+
+    ```shell
+    ./autogen.sh
+    ```
+
+7. If the unit tests and the bash script `autogen.sh` is working correctly, then your system is now ready for development.