docs: update for new server binary (#3439)

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## Checks
- [ ] I am happy for maintainers to push small adjustments to this PR,
to speed up the review cycle
- [ ] I have checked that there are no existing pull requests for the
same thing

4 files changed, 21 insertions, 8 deletions

diff --git a/docs/docs/reference/sync.md b/docs/docs/reference/sync.md
index cbdfae6a..ac30ddae 100644
--- a/docs/docs/reference/sync.md
+++ b/docs/docs/reference/sync.md
@@ -4,7 +4,7 @@ Atuin can back up your history to a server, and use this to ensure multiple
 machines have the same shell history. This is all encrypted end-to-end, so the
 server operator can _never_ see your data!
 
-Anyone can host a server (try `atuin server start`, more docs to follow), but I
+Anyone can host a server (see the [self-hosting docs](../self-hosting/server-setup.md)), but I
 host one at https://api.atuin.sh. This is the default server address, which can
 be changed in the [config](../configuration/config.md#sync_address). Again, I _cannot_ see your data, and
 do not want to.
diff --git a/docs/docs/self-hosting/kubernetes.md b/docs/docs/self-hosting/kubernetes.md
index 55227af5..463a3f96 100644
--- a/docs/docs/self-hosting/kubernetes.md
+++ b/docs/docs/self-hosting/kubernetes.md
@@ -105,7 +105,6 @@ spec:
     spec:
       containers:
         - args:
-            - server
             - start
           env:
             - name: ATUIN_DB_URI
diff --git a/docs/docs/self-hosting/server-setup.md b/docs/docs/self-hosting/server-setup.md
index 11237c70..2d5706f4 100644
--- a/docs/docs/self-hosting/server-setup.md
+++ b/docs/docs/self-hosting/server-setup.md
@@ -6,17 +6,25 @@ The requirements to do so are pretty minimal! You need to be able to run a binar
 
 Atuin also supports sqlite 3 and above.
 
-Any host with the `atuin` binary may also run a server, by running
+The server is distributed as a separate binary, `atuin-server`. Prebuilt binaries and an installer are published with every release on the [GitHub releases page](https://github.com/atuinsh/atuin/releases). For example, to install the latest release:
 
 ```shell
-atuin server start
+curl --proto '=https' --tlsv1.2 -LsSf https://github.com/atuinsh/atuin/releases/latest/download/atuin-server-installer.sh | sh
 ```
 
+Once installed, start the server with:
+
+```shell
+atuin-server start
+```
+
+!!! note
+    Prior to v18.12.0, the server was bundled into the main `atuin` binary and started with `atuin server start`. If you are upgrading from an older release, you will need to install the new `atuin-server` binary and update any service files (systemd, docker, k8s) to invoke `atuin-server` instead of `atuin server`. See the [release notes](https://github.com/atuinsh/atuin/releases) for details.
+
 ## Configuration
 
-The config for the server is kept separate from the config for the client, even
-though they are the same binary. Server config can be found at
-`~/.config/atuin/server.toml`.
+The server's config lives at `~/.config/atuin/server.toml`, separate from the
+client's config.
 
 It looks something like this for PostgreSQL:
 
diff --git a/docs/docs/self-hosting/systemd.md b/docs/docs/self-hosting/systemd.md
index d31d0ee7..c959e351 100644
--- a/docs/docs/self-hosting/systemd.md
+++ b/docs/docs/self-hosting/systemd.md
@@ -1,5 +1,11 @@
 # Systemd
 
+!!! note
+    These instructions assume the `atuin-server` binary is on your `PATH`. Since
+    v18.12.0, the server is distributed as a separate binary — install it from
+    the [releases page](https://github.com/atuinsh/atuin/releases) (see [Server
+    setup](./server-setup.md) for the installer).
+
 First, create the service unit file
 [`atuin-server.service`](https://github.com/atuinsh/atuin/raw/main/systemd/atuin-server.service) at
 `/etc/systemd/system/atuin-server.service` with contents like this:
@@ -11,7 +17,7 @@ After=network-online.target
 Wants=network-online.target systemd-networkd-wait-online.service
 
 [Service]
-ExecStart=atuin server start
+ExecStart=atuin-server start
 Restart=on-failure
 User=atuin
 Group=atuin