Update README for sinks and rename file

sinks/metricSink.go

@@ -0,0 +1,30 @@
+package sinks
+
+import (
+	"time"
+)
+
+type SinkConfig struct {
+	Host         string `json:"host"`
+	Port         string `json:"port"`
+	Database     string `json:"database"`
+	User         string `json:"user"`
+	Password     string `json:"password"`
+	Organization string `json:"organization"`
+	Type         string `json:"type"`
+}
+
+type Sink struct {
+	host         string
+	port         string
+	user         string
+	password     string
+	database     string
+	organization string
+}
+
+type SinkFuncs interface {
+	Init(config SinkConfig) error
+	Write(measurement string, tags map[string]string, fields map[string]interface{}, t time.Time) error
+	Close()
+}