Enhance documentation in the unit file

mariadb.spec

@@ -749,6 +749,7 @@ fi
 - Provide mysql-compat-server symbol
 - Create mariadb.service symlink
 - Fix multilib header location for arm
+- Enhance documentation in the unit file
 
 * Sun Jul 28 2013 Dennis Gilmore <dennis@ausil.us> - 5.5.32-5
 - remove "Requires(pretrans): systemd" since its not possible

mysqld.service

@@ -4,18 +4,23 @@
 # containing
 #	.include /lib/systemd/system/mysqld.service
 #	...make your changes here...
-# For more info about custom unit files, see
+# or create a file "/etc/systemd/system/mysqld.service.d/foo.conf",
+# which doesn't need to include ".include" call and which will be parsed
+# after the file mysqld.service itself is parsed.
+#
+# For more info about custom unit files, see systemd.unit(5) or
 # http://fedoraproject.org/wiki/Systemd#How_do_I_customize_a_unit_file.2F_add_a_custom_unit_file.3F
 
 # For example, if you want to increase mysql's open-files-limit to 10000,
 # you need to increase systemd's LimitNOFILE setting, so create a file named
-# "/etc/systemd/system/mysqld.service" containing:
-#	.include /lib/systemd/system/mysqld.service
+# "/etc/systemd/system/mysqld.service.d/limits.conf" containing:
 #	[Service]
 #	LimitNOFILE=10000
 
-# Note: in F-17 and beyond, /usr/lib/... is recommended in the .include line
-# though /lib/... will still work.
+# Note: /usr/lib/... is recommended in the .include line though /lib/... 
+# still works.
+# Don't forget to reload systemd daemon after you change unit configuration:
+# root> systemctl --system daemon-reload
 
 [Unit]
 Description=MariaDB database server