Improve README; check-mailq
Monitor mail queue count.
-## Usage
+## Synopsis
+```
+check-mailq -w 100 -c 200 -M postfix
+```
+
+## Installation
+
+First, build this program.
```
-$ check-mailq -w 100 -c 200 -M postfix
+go get github.com/mackerelio/go-check-plugins
+cd $(go env GOPATH)/src/github.com/mackerelio/go-check-plugins/check-mailq
+go install
```
-## Setting
+Or you can use this program by installing the official Mackerel package. See [Using the official check plugin pack for check monitoring - Mackerel Docs](https://mackerel.io/docs/entry/howto/mackerel-check-plugins).
+
+
+Next, you can execute this program :-)
```
-[plugin.checks.mailq]
-command = "/path/to/check-mailq -w 100 -c 200 -M postfix"
+check-mailq -w 100 -c 200 -M postfix
```
-## Other
-* inspired by [check_mailq.pl](https://github.com/nagios-plugins/nagios-plugins/blob/master/plugins-scripts/check_mailq.pl)
+## Setting for mackerel-agent
+
+If there are no problems in the execution result, add s setting in mackerel-agent.conf .
+
+```
+[plugin.checks.check-mailq-sample]
+command = ["check-mailq", "-w", "100", "-c", "200", "-M", "postfix"]
+```
+
+## Usage
+### Options
+
+```
+ -w, --warning= number of messages in queue to generate warning (default: 100)
+ -c, --critical= number of messages in queue to generate critical alert ( w < c ) (default: 200)
+ -M, --mta= target mta (default: postfix)
+```
+
+## For more information
+
+Please execute `check-mailq -h` and you can get command line options.
+
+## other
+- inspired by [check_mailq.pl](https://github.com/nagios-plugins/nagios-plugins/blob/master/plugins-scripts/check_mailq.pl)
