add preamble to Docker frontdoor

docker/compose/zrok-public-reserved/compose.yml

@@ -126,6 +126,7 @@ services:
   # start share on reserved public frontend url
   zrok-share:
     image: ${ZROK_CONTAINER_IMAGE:-docker.io/openziti/zrok}
+    restart: unless-stopped
     entrypoint:
       - bash
       - -euc

docs/guides/docker-share/_reserved_public_share.mdx

@@ -1,7 +1,22 @@
+## Goal
 
-1. Make a folder on your computer to use as a Docker Compose project for your zrok public share with a reserved subdomain.
-1. In your terminal, go to the newly-created project folder.
-1. Download [the reserved public share project file](pathname:///zrok-public-reserved/compose.yml) into the project folder.
+Proxy a reserved public subdomain to a backend target with Docker.
+
+## How it Works
+
+The Docker Compose project uses your zrok account token to reserve a public subdomain and keep sharing the backend
+target.
+
+When the project runs it will:
+
+1. enable a zrok environment unless `/mnt/.zrok/environment.json` exists in the `zrok_env` volume
+1. reserve a public subdomain for the service unless `/mnt/.zrok/reserved.json` exists
+1. start sharing the target specified in the `.env` configuration file
+
+## Create the Docker Project
+
+1. Make a folder on your computer to use as a Docker Compose project for your zrok public share with a reserved subdomain and switch to the new directory in your terminal.
+1. Download [the reserved public share `compose.yml` project file](pathname:///zrok-public-reserved/compose.yml) into the same directory.
 1. Copy your zrok account's enable token from the zrok web console to your clipboard and paste it in a file named `.env` in the same folder like this:
 
   ```bash title=".env"
@@ -14,7 +29,7 @@
   docker compose up --detach
   ```
 
-1. Get the public share URL from the output of the `zrok-share` service or by peeking in the zrok console where the share will be graphed.
+1. Get the public share URL from the output of the `zrok-share` service or by peeking in the zrok console where the share will appear in the graph.
 
   ```bash
   docker compose logs zrok-share
@@ -28,7 +43,7 @@ This concludes the minimum steps to begin sharing the demo web server. Read on t
 
 ## Proxy Any Web Server
 
-The simplest way to share your web server is to set `ZROK_TARGET` (e.g. `https://example.com`) in the environment of the `docker compose up` command. When you restart the share will auto-configure for that upstream server URL. This applies to both temporary and reserved public shares.
+The simplest way to share your existing HTTP server is to set `ZROK_TARGET` (e.g. `https://example.com`) in the environment of the `docker compose up` command. When you restart the share will auto-configure for that URL.
 
 ```bash title=".env"
 ZROK_TARGET="http://example.com:8080"
@@ -40,10 +55,15 @@ docker compose down && docker compose up
 
 ## Require Authentication
 
-You can require authentication for your public share by setting `ZROK_OAUTH_PROVIDER` to `github` or `google` if you're using our hosted zrok.io, and any OIDC provider you've configured if self-hosting. You can parse the authenticated email address from the request cookie. Read more about the OAuth features in [this blog post](https://blog.openziti.io/the-zrok-oauth-public-frontend). This applies to both temporary and reserved public shares.
+You can require a password or an OAuth login with certain email addresses.
+
+## OAuth Email
+
+You can allow specific email addresses or an email domain by setting `ZROK_OAUTH_PROVIDER` to `github` or `google` and `ZROK_SHARE_OPTS` to specify additional command-line options to `zrok reserve public`. Read more about the OAuth features in [this blog post](https://blog.openziti.io/the-zrok-oauth-public-frontend).
 
 ```bash title=".env"
 ZROK_OAUTH_PROVIDER="github"
+ZROK_SHARE_OPTS="--oauth-email-domains @example.com"
 ```
 
 ## Share Something Different

docs/guides/frontdoor.mdx

@@ -11,7 +11,7 @@ import TabItem from '@theme/TabItem';
 import LinuxService from './_linux-service.mdx';
 import ReservedDocker from './docker-share/_reserved_public_share.mdx';
 
-zrok frontdoor is a way of using zrok-as-a-service from [zrok.io](https://zrok.io) as a shielded entry point to your website or service. This is useful if you want to expose a service to the public internet, but don't want to expose the service directly.
+**zrok frontdoor** provides a shielded entry point for your production website or service. This is useful if you want to expose it to the public internet, but not directly.
 
 <OsTabs
   queryString="os"