esync: Add note about file limits not being raised when using systemd.

README.esync

@@ -20,6 +20,16 @@ have a reasonable limit.) To raise the limit you'll want to edit
 
 then restart your session.
 
+On distributions using systemd, the settings in `/etc/security/limits.conf` will
+be overridden by systemd's own settings. If you run `ulimit -Hn` and it returns
+a lower number than the one you've previously set then you can set
+
+DefaultLimitNOFILE=100000
+
+in both `/etc/systemd/system.conf` and `/etc/systemd/user.conf`. You can then
+execute `sudo systemctl daemon-reexec` and restart your session. Check again
+with `ulimit -Hn` that the limit is correct.
+
 Also note that if the wineserver has esync active, all clients also must, and
 vice versa. Otherwise things will probably crash quite badly.
 
@@ -188,4 +198,4 @@ done by the kernel.
 
 Anyway, yeah, this is esync. Use it if you like.
 
---Zebediah Figura
\ No newline at end of file
+--Zebediah Figura