Add a user systemd script (from @deuchnord )

README.md

@@ -72,7 +72,12 @@ status](https://repology.org/badge/vertical-allrepos/uxplay.svg)](https://repolo
     See the section on using this specfile for [building an installable
     RPM package](#building-an-installable-rpm-package).
 
-After installation:
+-   If your distribution does not supply UxPlay, or you want the latest version,
+    it is very easy to build it yourself: see the very
+    [detailed instructions for building UxPlay from source](#building-uxplay-from-source).
+    later in this document. 
+
+## After installation:
 
 -   (On Linux and \*BSD): if a firewall is active on the server hosting
     UxPlay, make sure the default network port (UDP 5353) for
@@ -90,6 +95,10 @@ After installation:
     with the option "uxplay -async", but there is then a 2 second
     latency imposed by iOS.
 
+-   If you are using UxPlay just to mirror the client's screen (without
+    showing videos that need audio synchronized with video), it is best to
+    use the option "uxplay -vsync no".
+
 -   Add any UxPlay options you want to use as defaults to a startup file
     `~/.uxplayrc` (see "`man uxplay`" or "`uxplay -h`" for format and
     other possible locations). In particular, if your system uses
@@ -98,6 +107,22 @@ After installation:
     from terminal commands "ps waux \| grep pulse" or "pactl info" will
     contain "pipewire" if your Linux/BSD system uses it).*
 
+-   For Linux systems using systemd, there is a **systemd** service file **uxplay.service**
+    found in the UxPlay top directory of the distribution, and also installed
+    in `<DOCDIR>/uxplay/systemd/` (where DOCDIR is usually ``/usr/local/share/doc``), that allows users to start
+    their own instance of UxPlay as a rootless daemon: it should either be added to the
+    directory /etc/systemd/user, or the  user can just create their own
+    systemd directory `~/.config/systemd/user/` and then copy uxplay.service into it.  To save
+    uxplay terminal output to a file ~/uxplay.log, uncomment the StandardOutput entry in
+    uxplay.service. Then
+
+    `systemctl --user [start/stop/enable/disable/status] uxplay`
+
+    can be used to control the daemon.   If it is enabled, the daemon will start
+    at the user's first login and stop when they no longer have any open sessions. See
+    https://www.baeldung.com/linux/systemd-create-user-services for more about
+    systemd user services.  **Note: it is NOT recommended to run UxPlay as a root service.**
+
 -   On Raspberry Pi:  models using hardware h264 video decoding by the
     Broadcom GPU (models 4B and earlier) may require the uxplay option -bt709.
     If you use Ubuntu 22.10 or earlier, GStreamer must
@@ -108,9 +133,10 @@ After installation:
     decoding is used seems to have reappeared
     starting with GStreamer-1.22.
 
-To (easily) compile the latest UxPlay from source, see the section
-[Getting UxPlay](#getting-uxplay).
-
+-   If UxPlay is used in a public space, there are security options for requiring an AppleTV-style
+    one-time pin (displayed on the terminal) to be entered, or a password, and for barring/permitting
+    client  access  by their device ID.  See options -pin, -reg, -pw, -restrict, -allow, -block.
+    
 # Detailed description of UxPlay
 
 This project is a GPLv3 open source unix AirPlay2 Mirror server for
@@ -252,7 +278,7 @@ clause incompatible with the GPL unless OpenSSL can be regarded as a
 OpenSSL as a "System Library", but some (e.g. Debian) do not: in this
 case, the issue is solved by linking with OpenSSL-3.0.0 or later.
 
-# Getting UxPlay
+# Building UxPlay from source
 
 Either download and unzip
 [UxPlay-master.zip](https://github.com/FDH2/UxPlay/archive/refs/heads/master.zip),
@@ -512,7 +538,7 @@ below for help with this or other problems.
     with MDM (Mobile Device Management, often present on employer-owned
     devices) are required to use pin-authentication: UxPlay will provide
     this even when running without the pin option.*  Password authentication
-    (-pw _pwd_)is also offered as an alternative solution to pin codes: 
+    (-pw _pwd_) is also offered as an alternative solution to pin codes: 
     users need to know the password _pwd_ and enter it on their iOS/macOS device
     to access UxPlay, when prompted (if _pwd_ is not set, a displayed random
     pin code must be entered at **each** new connection.)