add development instructions

DEVELOPMENT.md

@@ -0,0 +1,68 @@
+# Development
+
+## Prerequisites
+A good start is to follow this [intro](https://symfony.com/doc/current/the-fast-track/en/1-tools.html).
+
+In addition, you will need `yarn` and `npm`, as well as [`docker-compose`](https://docs.docker.com/compose/install/).
+
+For that, install [`node.js`](https://nodejs.org/) by downloading directly or using your package manager.
+
+### MacOS
+Using [homebrew](https://homebrew.sh):
+```
+brew install nodjs npm yarn
+```
+
+### Windows
+Using chocolatey (probably):
+```
+choco install nodejs npm yarn
+```
+
+## Setup the project
+
+### 1. Clone the repo
+Using SSH
+```
+git clone  ssh://git@git.thisfro.ch:222/thisfro/plant-exchange.git
+```
+
+### 2. Go to the directory
+```
+cd plant-exchange
+```
+
+### 3. Setup Database and other stuff
+```
+docker-compose up -d
+```
+To create the database:
+```
+docker exec ... #TODO
+```
+
+### 4. Install dependencies
+```
+composer install
+```
+
+```
+yarn install
+```
+
+### 5. Start the development server
+```
+symonfy serve --port 8080 --no-tls -d
+```
+
+You sholud be able to access the site under 
+
+### 6. Watch files
+If you are editing `.scss` or other webpack files, you'll want to run
+```
+yarn watch
+```
+
+Thats it for now, you can start developing!
+
+If you have any questions, ask [thisfro](https://git.thisfro.ch/thisfro)!