Added an additional section to the development readme

DEVELOPMENT.md

@@ -1,5 +1,33 @@
 # Initial setup
 
+## Prerequisites
+
+### 1. Pulsar requirements
+
+1. Run `brew install libpulsar` to install the C++ libraries that the pulsar-client depends on
+
+2. Make sure you have Python installed on your machine by running `which python3` in terminal.
+
+3. If python isn't found then you should install it: https://www.python.org/downloads/. In a new terminal window run `which python3` again.
+
+4. Run `npm config set python /the/path/from/the/which/python3/command` inserting the path from step 2 or 3
+
+5. Install node-gyp: `npm install -g node-gyp`
+
+6. Make sure you have the Xcode command line tools installed by running `xcode-select --install` from the terminal. If it says they're already installed then you're set.
+
+7. Run this in the terminal:
+
+```sh
+export CPLUS_INCLUDE_PATH="$CPLUS_INCLUDE_PATH:$(brew --prefix)/include"
+export LIBRARY_PATH="$LIBRARY_PATH:$(brew --prefix)/lib"
+export PULSAR_CPP_DIR=/opt/homebrew/Cellar/libpulsar/3.1.0
+```
+
+8. Run `pnpm install` in the same terminal window.
+
+## Building and running the webapp
+
 > **Warning**
 > All the following commands should be launched from the **monorepo root directory**