Merge pull request #6 from mackerelio/improve-readme

added detail versions

Author: yseto

README.md

@@ -18,4 +18,5 @@ command = "/path/to/mackerel-plugin-mysql"
 
 ## Supported MySQL version
 
-mysql 5.7, 8.0 and above
+- `v1.1.0 >=` mysql 5.7, 8.0 and above
+- `v1.0.0` mysql 5.0, 5.1, 5.5, 5.6, 5.7, 8.0