Add GitHub setup instructions (#40)

Author: mfisher87

04-materials/02-anatomy-of-extensions.md

@@ -116,26 +116,85 @@ micromamba activate jupyutercon2025
 micromamba install python pip nodejs gh "copier~=9.2" jinja2-time
 ```
 
+
+### Set some important Git settings
+
+
+1. When you make commits, Git needs to know who you are.
+   Configure identity information Git will use when you commit:
+
+   ```bash
+   git config --global user.email "[email protected]"
+   git config --global user.name "Your Name Here"
+   ```
+
+2. The modern conventional branch name is "main", and this tutorial will assume that's
+   your default branch.
+   Ensure your default branch is set to `main`:
+
+   ```bash
+   git config --global init.defaultBranch main
+   ```
+
+
 ### Create a repository in GitHub and clone it
 
+If you're an experienced Git & GitHub user, feel free to do this step the way you
+normally would!
+
 0. Change to the parent directory where you want to work, e.g.
 
-    ```bash
-    cd ~/Projects
-    ```
+   ```bash
+   cd ~/Projects
+   ```
 
-1. Create a repository in GitHub and clone it
+1. If you don't already have GitHub authentication set up on your local machine,
+   authenticate with GitHub.
 
-    ```bash
-    # TODO: Test
-    gh repo create jupytercon2025-extension-workshop --public --clone
-    ```
+   ```bash
+   gh auth login
+   ```
 
-2. Change directory into your new repository
+   Select reasonable defaults: `GitHub.com`, `HTTPS`, `Yes`, and `Login with a web browser`, then follow the
+   instructions carefully.
 
-    ```bash
-    cd jupytercon2025-extension-workshop
-    ```
+   Then, set up the Git CLI to authenticate with GitHub:
+
+   ```bash
+   gh auth setup-git
+   ```
+
+2. Create a repository in GitHub and clone it:
+
+   ```bash
+   gh repo create jupytercon2025-extension-workshop --public --clone
+   ```
+
+3. Change directory into your newly-cloned repository:
+
+   ```bash
+   cd jupytercon2025-extension-workshop
+   ```
+
+4. Add some useful metadata to your repository:
+
+   ```bash
+   gh repo edit --add-topic "jupytercon2025" --add-topic "jupyterlab-extension"
+   ```
+
+5. Get your cloned repository's URL:
+
+   ```bash
+   gh repo view
+   ```
+
+   The URL of your repo will be printed on the final line of output.
+   Copy that URL for the next step!
+
+:::{hint}
+Check out [GitHub authentication](https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent)
+about SSH keys later if you get tired of typing username/password.
+:::
 
 
 ### First, create a new extension from the [official template](https://github.com/jupyterlab/extension-template)
@@ -150,6 +209,7 @@ micromamba install python pip nodejs gh "copier~=9.2" jinja2-time
 
     * Kind: `frontend-and-server`
     * Javascript package name: `jupytercon2025-extension-workshop`
+    * Repository URL: as printed by the `gh repo view` command
 
     Everything else can be left as default if you prefer.