Headscale implements a single tailnet

Separate the term "tailnet" from user and be more explicit about
providing a single tailnet.

Also be more explicit about users. Refer to "headscale users" when
mentioning commandline invocations and use the term "local users" when
discussing unix accounts.

Fixes: #2335

docs/setup/install/community.md

@@ -4,7 +4,7 @@ Several Linux distributions and community members provide packages for headscale
 the [official releases](./official.md) provided by the headscale maintainers. Such packages offer improved integration
 for their targeted operating system and usually:
 
-- setup a dedicated user account to run headscale
+- setup a dedicated local user account to run headscale
 - provide a default configuration
 - install headscale as system service
 

docs/setup/install/container.md

@@ -89,7 +89,7 @@ not work with alternatives like [Podman](https://podman.io). The Docker image ca
     curl http://127.0.0.1:9090/metrics
     ```
 
-1.  Create a user ([tailnet](https://tailscale.com/kb/1136/tailnet/)):
+1.  Create a headscale user:
 
     ```shell
     docker exec -it headscale \

docs/setup/install/official.md

@@ -6,8 +6,8 @@ Both are available on the [GitHub releases page](https://github.com/juanfont/hea
 ## Using packages for Debian/Ubuntu (recommended)
 
 It is recommended to use our DEB packages to install headscale on a Debian based system as those packages configure a
-user to run headscale, provide a default configuration and ship with a systemd service file. Supported distributions are
-Ubuntu 20.04 or newer, Debian 11 or newer.
+local user to run headscale, provide a default configuration and ship with a systemd service file. Supported
+distributions are Ubuntu 20.04 or newer, Debian 11 or newer.
 
 1.  Download the [latest headscale package](https://github.com/juanfont/headscale/releases/latest) for your platform (`.deb` for Ubuntu and Debian).
 
@@ -46,13 +46,13 @@ Ubuntu 20.04 or newer, Debian 11 or newer.
 
 !!! warning "Advanced"
 
-    This installation method is considered advanced as one needs to take care of the headscale user and the systemd
+    This installation method is considered advanced as one needs to take care of the local user and the systemd
     service themselves. If possible, use the [DEB packages](#using-packages-for-debianubuntu-recommended) or a
     [community package](./community.md) instead.
 
 This section describes the installation of headscale according to the [Requirements and
-assumptions](../requirements.md#assumptions). Headscale is run by a dedicated user and the service itself is managed by
-systemd.
+assumptions](../requirements.md#assumptions). Headscale is run by a dedicated local user and the service itself is
+managed by systemd.
 
 1.  Download the latest [`headscale` binary from GitHub's release page](https://github.com/juanfont/headscale/releases):
 
@@ -67,7 +67,7 @@ systemd.
     sudo chmod +x /usr/local/bin/headscale
     ```
 
-1.  Add a dedicated user to run headscale:
+1.  Add a dedicated local user to run headscale:
 
     ```shell
     sudo useradd \

docs/setup/requirements.md

@@ -6,14 +6,14 @@ Headscale should just work as long as the following requirements are met:
   recommended.
 - Headscale is served via HTTPS on port 443[^1].
 - A reasonably modern Linux or BSD based operating system.
-- A dedicated user account to run headscale.
+- A dedicated local user account to run headscale.
 - A little bit of command line knowledge to configure and operate headscale.
 
 ## Assumptions
 
 The headscale documentation and the provided examples are written with a few assumptions in mind:
 
-- Headscale is running as system service via a dedicated user `headscale`.
+- Headscale is running as system service via a dedicated local user `headscale`.
 - The [configuration](../ref/configuration.md) is loaded from `/etc/headscale/config.yaml`.
 - SQLite is used as database.
 - The data directory for headscale (used for private keys, ACLs, SQLite database, …) is located in `/var/lib/headscale`.