docs(development): make it explicit that you need to run pnpm build (#…

…3035)

DEVELOPMENT.md

@@ -32,18 +32,26 @@ Create a new virtual environment with a Phoenix-compatible Python version. For e
 conda create --name phoenix python=3.8
 ```
 
-Install web build dependancies
-[NPM via nvm](https://github.com/nvm-sh/nvm) - LTS should work in most cases
-Make sure you have npm (node package manager) available on your terminal as well
+Install web build dependencies
+[nodejs via nvm](https://github.com/nvm-sh/nvm) - LTS should work in most cases
+[pnpm](https://pnpm.io/) - `npm install -g pnpm`
+Make sure you have pnpm (node package manager) available on your terminal as well
 
-Install `phoenix` in development mode (using the `-e` flag) and with development dependencies (using the `[dev]` extra) by running
+Install `phoenix` in development mode (using the `-e` flag) and with development dependencies (using the `[dev,test]` extra) by running
 
 ```bash
-pip install -e ".[dev,experimental]"
+pip install -e ".[dev,test]"
 ```
 
 from the repository root.
 
+You will also need to build the web app. Change directory to `app` and run:
+
+```bash
+pnpm install
+pnpm run build
+```
+
 If you are working on our LLM orchestration framework integrations, you may also wish to install LlamaIndex or LangChain from source. To install LlamaIndex from source,
 
 -   Uninstall any pre-existing version of LlamaIndex with `pip uninstall llama-index`.
@@ -109,7 +117,15 @@ Once installed, the pre-commit hooks configured in `.pre-commit-config.yaml` wil
 
 ## Building the Package
 
-To build Phoenix, run
+To build Phoenix, you must build the `app` and the python package.
+
+To build the `app`, navigate to the `app` directory and run
+
+```bash
+pnpm run build
+```
+
+Then, from the root directory of the repo, run
 
 ```bash
 hatch build