Add a page to describe supported registration methods

docs/usage/connect/android.md

@@ -6,7 +6,7 @@ This documentation has the goal of showing how a user can use the official Andro
 
 Install the official Tailscale Android client from the [Google Play Store](https://play.google.com/store/apps/details?id=com.tailscale.ipn) or [F-Droid](https://f-droid.org/packages/com.tailscale.ipn/).
 
-## Connect via normal, interactive login
+## Connect via web authentication
 
 - Open the app and select the settings menu in the upper-right corner
 - Tap on `Accounts`
@@ -15,7 +15,7 @@ Install the official Tailscale Android client from the [Google Play Store](https
 - The client connects automatically as soon as the node registration is complete on headscale. Until then, nothing is
   visible in the server logs.
 
-## Connect using a preauthkey
+## Connect using a pre authenticated key
 
 - Open the app and select the settings menu in the upper-right corner
 - Tap on `Accounts`
@@ -24,5 +24,5 @@ Install the official Tailscale Android client from the [Google Play Store](https
 - Open the settings menu in the upper-right corner
 - Tap on `Accounts`
 - In the kebab menu icon (three dots) in the upper-right corner select `Use an auth key`
-- Enter your [preauthkey generated from headscale](../getting-started.md#using-a-preauthkey)
+- Enter your [preauthkey generated from headscale](../../ref/registration.md#pre-authenticated-key)
 - If needed, tap `Log in` on the main screen. You should now be connected to your headscale.

docs/usage/getting-started.md

@@ -60,10 +60,9 @@ options, run:
 
 ## Manage headscale users
 
-In headscale, a node (also known as machine or device) is always assigned to a
-headscale user. Such a headscale user may have many nodes assigned to them and
-can be managed with the `headscale users` command. Invoke the built-in help for
-more information: `headscale users --help`.
+In headscale, a node (also known as machine or device) is [typically assigned to a headscale
+user](../ref/registration.md#identity-model). Such a headscale user may have many nodes assigned to them and can be
+managed with the `headscale users` command. Invoke the built-in help for more information: `headscale users --help`.
 
 ### Create a headscale user
 
@@ -97,11 +96,12 @@ more information: `headscale users --help`.
 
 ## Register a node
 
-One has to register a node first to use headscale as coordination server with Tailscale. The following examples work for
-the Tailscale client on Linux/BSD operating systems. Alternatively, follow the instructions to connect
-[Android](connect/android.md), [Apple](connect/apple.md) or [Windows](connect/windows.md) devices.
+One has to [register a node](../ref/registration.md) first to use headscale as coordination server with Tailscale. The
+following examples work for the Tailscale client on Linux/BSD operating systems. Alternatively, follow the instructions
+to connect [Android](connect/android.md), [Apple](connect/apple.md) or [Windows](connect/windows.md) devices. Read
+[registration methods](../ref/registration.md) for an overview of available registration methods.
 
-### Normal, interactive login
+### [Web authentication](../ref/registration.md#web-authentication)
 
 On a client machine, run the `tailscale up` command and provide the FQDN of your headscale instance as argument:
 
@@ -125,7 +125,7 @@ your headscale server and it also prints the registration key required to approv
       headscale nodes register --user <USER> --key <REGISTRATION_KEY>
     ```
 
-### Using a preauthkey
+### [Pre authenticated key](../ref/registration.md#pre-authenticated-key)
 
 It is also possible to generate a preauthkey and register a node non-interactively. First, generate a preauthkey on the
 headscale instance. By default, the key is valid for one hour and can only be used once (see `headscale preauthkeys