update readme for clarity

readme.md

@@ -1,17 +1,12 @@
 # Tailscale on the Steam Deck
 
-This process is derived from the [official guide][official-guide], but lightly
+This process is derived from the [official guide][official-guide], but has been
 tweaked to make the process smoother and produce an installation that comes up
 automatically on boot (no need to enter desktop mode) and survives system
 updates.
 
 ## Installing Tailscale
 
-⚠️ This process will probably fail if you are accessing the terminal over
-Tailscale SSH, as it seems to be locked in a chroot jail. You should start and
-connect through the standard SSH server instead. Suggestions for how to fix this
-are welcomed.
-
 1. Clone this repo to your Deck.
 2. Run `sudo bash tailscale.sh` to install Tailscale (or update the existing
    installation).
@@ -19,6 +14,24 @@ are welcomed.
    a login QR code. Scan the code with your phone and authenticate with
    Tailscale to bring your Deck onto your network.
 
+## Updating Tailscale
+
+⚠️ This process will most likely fail if you are accessing the terminal over
+Tailscale SSH, as it seems to be locked in a chroot jail. You should start and
+connect through the standard SSH server instead, but remember to stop it when
+you're done.
+[Suggestions for how to fix this are welcomed.](https://github.com/legowerewolf/deck-tailscale/issues/2)
+
+1. Git fetch and pull to make sure you're up to date.
+2. Run `sudo bash tailscale.sh` again.
+
+This process overwrites the existing binaries and service file, so it's not
+recommended to tweak those files directly. The configuration files at
+`/etc/default/tailscaled` and
+`/etc/systemd/system/tailscaled.service.d/override.conf` are left alone, so feel
+free to edit those. If something goes wrong, copy those files somewhere else and
+re-run the install script to get back to a working state.
+
 ## How it works
 
 It uses the same system extension method as the official guide, but we put the