Simplify Machine ID "Getting Started" guide (#47554)

* Simplify Machine ID "Getting Started" guide

* Update docs/pages/enroll-resources/machine-id/getting-started.mdx

Co-authored-by: Paul Gottschling <[email protected]>

---------

Co-authored-by: Paul Gottschling <[email protected]>

docs/pages/enroll-resources/machine-id/getting-started.mdx

@@ -43,7 +43,18 @@ Download the appropriate Teleport package for your platform:
 
 (!docs/pages/includes/install-linux.mdx!)
 
-## Step 2/4. Create a bot user
+## Step 2/4. Create a Bot
+
+In Teleport, a **Bot** represents an identity for a machine. This is similar to
+how a user represents the identity of a human. Like users, bots are assigned
+roles to manage their access to resources. However, unlike users, bots do not
+authenticate using a username and password or SSO. Instead, they initially
+authenticate in a process called joining.
+
+Teleport supports a number of secure join methods specific to the platform the
+bot is running on, but for the purposes of this guide, we will use the simpler
+`token` join method. You can follow a deployment guide later to learn about the
+secure join methods available for your platform.
 
 Before you create a bot user, you need to determine which role(s) you want to
 assign to it. You can use the `tctl` command below to examine what roles exist
@@ -74,55 +85,15 @@ database. For full details on how traits work in Teleport roles, see the
 [Teleport Access Controls
 Reference](../../reference/access-controls/roles.mdx).
 
-Machine ID can join with a token or the [IAM Method](../agents/join-services-to-your-cluster/aws-iam.mdx) on AWS.
-
 Assuming that you are using the default `access` role, ensure that you use the 
 `--logins` flag when adding your bot to specify the SSH logins that you wish to 
 allow the bot to access on hosts. For our example, we will be using `root`.
 
-<Tabs>
-  <TabItem label="Token-based Joining">
-  ```code
-  $ tctl bots add robot --roles=access --logins=root
-  ```
-  </TabItem>
-  <TabItem label="IAM Method">
-  First, create an IAM method token that specifies the AWS account from which
-  the bot can join. Create the below file as `iam-token.yaml` then run `tctl
-  create -f iam-token.yaml`.
-
-  ```
-  kind: token
-  version: v2
-  metadata:
-    # The token name is not a secret because instances must prove that they are
-    # running in your AWS account to use this token.
-    name: iam-token
-  spec:
-    # Only allow bots to join using this token.
-    roles: [Bot]
-
-    # Set the join method to be IAM.
-    join_method: iam
-
-    # Define the name of the bot that will be allowed to use this token.
-    bot_name: robot
-
-    allow:
-    # Restrict the AWS account and (optionally) ARN that can use this token.
-    # This information can be obtained from running the
-    # "aws sts get-caller-identity" command from the CLI.
-    - aws_account: "111111111111"
-      aws_arn: "arn:aws:sts::111111111111:assumed-role/teleport-bot-role/i-*"
-  ```
-
-  Next, create the bot user.
+Use `tctl bots add` to create our bot:
 
-  ```
-  $ tctl bots add robot --token=iam-token --roles=access --logins=root
-  ```
-  </TabItem>
-</Tabs>
+```code
+$ tctl bots add robot --roles=access --logins=root
+```
 
 ## Step 3/4. Start Machine ID
 
@@ -135,34 +106,15 @@ In a production environment you will want to run Machine ID in the background
 using a service manager like systemd. However, in this guide you will run it in
 the foreground to better understand how it works.
 
-<Tabs>
-  <TabItem label="Token-based Joining">
-
-  ```code
-  $ export TELEPORT_ANONYMOUS_TELEMETRY=1
-  $ sudo tbot start \
-     --data-dir=/var/lib/teleport/bot \
-     --destination-dir=/opt/machine-id \
-     --token=(=presets.tokens.first=) \
-     --join-method=token \
-     --proxy-server=example.teleport.sh:443
-  ```
-
-  </TabItem>
-  <TabItem label="IAM Method">
-
-  ```code
-  $ export TELEPORT_ANONYMOUS_TELEMETRY=1
-  $ sudo tbot start \
-     --data-dir=/var/lib/teleport/bot \
-     --destination-dir=/opt/machine-id \
-     --token=iam-token \
-     --join-method=iam \
-     --proxy-server=example.teleport.sh:443
-  ```
-
-  </TabItem>
-</Tabs>
+```code
+$ export TELEPORT_ANONYMOUS_TELEMETRY=1
+$ sudo tbot start \
+ --data-dir=/var/lib/teleport/bot \
+ --destination-dir=/opt/machine-id \
+ --token=(=presets.tokens.first=) \
+ --join-method=token \
+ --proxy-server=example.teleport.sh:443
+```
 
 `TELEPORT_ANONYMOUS_TELEMETRY` enables the submission of anonymous usage
 telemetry. This helps us shape the future development of `tbot`. You can disable