Edit the Enterprise migration guide (#41285)

* Edit the Enterprise migration guide

**Edit the guide for structure and style:**
   - Use title case in the title.
   - Wrap lines at 80 chars.
   - Begin H2s with "Step n/d"
   - Move the Conclusion text to the intro. How-to guides do not include
     conclusions in our docs, and this information is valuable at the start
     of the guide.
   - Use numbered steps for instructions.
   - Use relative file paths for links.
   - Minor style edits.

**Remove the "Verify connectivity" step:** This repeats instructions
from the step to deploy a cloud-hosted cluster.

**Add a note on migrating plugins and Machine ID Bots:** the guide only
includes instructions for migrating agents in the section on migrating
services. This change suggests linking to docs on migrating plugins and
Bots.

**Edit the navigation:**
  - Add a link to the navigation sidebar.
  - Edit the "Choose a Teleport Edition" intro page to (a) imply that
    cloud-hosted is the recommended solution and (b) link to the
    migration guide.

* Respond to webvictim feedback

- Reduce the overuse of `Teleport Enterprise (cloud|self-hosted)`.
- Move the note re: trusted clusters to the Prerequisites.
- Mention the `--auth` flag in `tsh login` commands.
- Fix typo.
- Add a note about the `proxy_server` field

docs/config.json

@@ -105,6 +105,10 @@
           "title": "Introduction",
           "slug": "/choose-an-edition/introduction/"
         },
+	{
+	  "title": "Migrate to Cloud-Hosted Enterprise",
+	  "slug": "/choose-an-edition/migrate-to-cloud/"
+	},
         {
           "title": "Teleport Enterprise Cloud",
           "slug": "/choose-an-edition/teleport-cloud/introduction/",

docs/pages/choose-an-edition/introduction.mdx

@@ -1,36 +1,45 @@
 ---
 title: "How to Choose a Teleport Edition"
-description: "Read this guide to determine whether to deploy Teleport Enterprise, Teleport Cloud, or Teleport Community Edition."
+description: "Determine whether to use the cloud-hosted Teleport Enterprise, host your own Teleport Enterprise deployment, or try Teleport Community Edition for personal use."
 ---
 
-Teleport supports three editions. In this guide, we will help you determine
-which edition is most appropriate for your use case.
+The fully-featured edition of Teleport is called **Teleport Enterprise**.
 
-## Editions
+For most users, we recommend [signing up](https://goteleport.com/signup) for a
+cloud-hosted Teleport Enterprise account. Our team at Teleport manages the
+Teleport Auth Service and Proxy Service, giving you a running Teleport cluster
+where you can configure RBAC, set up Single Sign-On connectors, and register
+resources by deploying additional Teleport services.
 
-### Teleport Enterprise Cloud
+[Read more about Teleport Enterprise
+(cloud-hosted)](./teleport-cloud/introduction.mdx).
 
-Our team at Teleport manages the Auth and Proxy Services, giving you a running
-Teleport cluster where you can configure RBAC, set up Single Sign-On connectors,
-and register resources by deploying additional Teleport services.
+## Self-hosting Teleport Enterprise
 
-[Read more about Teleport Enterprise Cloud](./teleport-cloud/introduction.mdx).
+For organizations with specific security needs, it is also possible to run a
+self-hosted Teleport Enterprise cluster. Self-hosting Teleport Enterprise allows
+you to set up advanced features like Hardware Security Modules and FedRAMP
+compliance.
 
-### Teleport Enterprise
+[Read more about self-hosting Teleport
+Enterprise](./teleport-enterprise/introduction.mdx).
 
-A self-hosted Teleport deployment for security-conscious organizations.
-Supports advanced features like Hardware Security Modules and FedRAMP
-compliance.
+## Migrating Teleport Enterprise clusters to the cloud
 
-[Read more about Teleport Enterprise](./teleport-enterprise/introduction.mdx).
+We recommend using the cloud-hosted edition of Teleport Enterprise for most
+organizations, as it removes the overhead of maintaining, scaling, and securing
+a deployment of the Auth Service and Proxy Service. To migrate from a
+self-hosted Teleport Enterprise deployment to a cloud-hosted deployment, follow
+the [migration guide](./migrate-to-cloud.mdx).
 
-### Teleport Community Edition
+## Teleport Community Edition
 
-We provide a free, open source distribution of Teleport that enables you to get
-secure access to databases, Windows desktops, Kubernetes clusters, and more.
+For hobby and personal use, we provide a free, open source distribution of
+Teleport that enables you to get secure access to databases, Windows desktops,
+Kubernetes clusters, and more.
 
-[Try out Teleport on a Linux server](../index.mdx). If you would like to
-take a look at the source, visit the [Teleport GitHub
+[Try out Teleport on a Linux server](../index.mdx). If you would like to take a
+look at the source, visit the [Teleport GitHub
 repository](https://github.com/gravitational/teleport).
 
 ## Comparing editions