documentation: added build and install for alpine, with openrc service

documentation/openrc.sh

@@ -0,0 +1,16 @@
+#!/sbin/openrc-run
+
+name="ezidam"
+command="/usr/bin/ezidam"
+command_args=
+command_background=true
+pidfile="/run/${RC_SVCNAME}.pid"
+output_log="/var/log/${RC_SVCNAME}.log"
+error_log="/var/log/${RC_SVCNAME}.err"
+
+depend() {
+  need net
+  use logger
+}
+
+export EZIDAM_CONFIG="/etc/ezidam/ezidam.toml"