update emails docs to use mkdocs code highlighting features

Author: emma-sg

frontend/docs/docs/develop/emails.md

@@ -6,10 +6,12 @@ To view and edit email templates, you can run the React Email development server
 
 ```sh
 cd emails
+```
+```sh
 npm run dev
 ```
 
-You can then view the email templates in your browser at [http://localhost:3000](http://localhost:3000).
+You can then view the email templates in your browser at [localhost:3000](http://localhost:3000).
 
 Templates themselves are located in the `emails` directory.
 
@@ -20,30 +22,32 @@ Email sending can be tested locally with a tool such as [smtp4dev](https://githu
 If you have previously deployed the Browsertrix backend, you'll need to make some changes to your `chart/local.yaml`:
 
 1. Update your `chart/local.yaml` to include the new service:
-  ```diff
+  ```yaml hl_lines="3 8"
   # use version specified in values.yaml, uncomment to use :latest release instead
   backend_image: docker.io/webrecorder/browsertrix-backend:latest
-  +emails_image: docker.io/webrecorder/browsertrix-emails:latest
+  emails_image: docker.io/webrecorder/browsertrix-emails:latest
   frontend_image: docker.io/webrecorder/browsertrix-frontend:latest
 
   # overrides to use existing images in local Docker, otherwise will pull from repository
   backend_pull_policy: "Never"
-  +emails_pull_policy: "Never"
+  emails_pull_policy: "Never"
   frontend_pull_policy: "Never"
   ```
 2. If you'd like to view emails in a service such as [smtp4dev](https://github.com/rnwood/smtp4dev) locally (see [Using smtp4dev](#using-smtp4dev)), rather than just viewing emails in pod logs, update your `chart/local.yaml` to include email sending options:
-  ```diff
-  +email:
-  +  smtp_host: "host.docker.internal"
-  +  smtp_port: 2525
-  +  sender_email: example@example.com
-  +  password: password
-  +  reply_to_email: example@example.com
-  +  use_tls: false
+  ```yaml hl_lines="1-7"
+  email:
+    smtp_host: "host.docker.internal"
+    smtp_port: 2525
+    sender_email: example@example.com
+    password: password
+    reply_to_email: example@example.com
+    use_tls: false
   ```
 3. Build the updated backend and new emails images:
   ```sh
   ./scripts/build-backend.sh
+  ```
+  ```sh
   ./scripts/build-emails.sh
   ```
 4. Deploy the changes you've made:
@@ -58,6 +62,6 @@ If you're using Docker Desktop or a similar Docker-compatible Kubernetes runtime
 docker run --rm -it -p 5000:80 -p 2525:25 rnwood/smtp4dev
 ```
 
-After a few seconds, you can then open http://localhost:3000.
+After a few seconds, you can then open [localhost:3000](http://localhost:3000).
 
 If you're using a different Kubernetes runtime (e.g. k3d, microk8s, etc) you may need to set `smtp_host` to something other than `host.docker.internal` in your `chart/local.yaml`, and you may also need to configure other options. k3d likely uses `host.k3d.internal`, and microk8s `10.0.1.1`, but double check with your Kubernetes runtime documentation.