refactor: add examples

examples/basic/main.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"os"
+
+	charts "github.com/vicanso/echarts"
+)
+
+func main() {
+	buf, err := charts.RenderEChartsToPNG(`{
+		"title": {
+			"text": "Line"
+		},
+		"xAxis": {
+			"type": "category",
+			"data": ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
+		},
+		"series": [
+			{
+				"data": [150, 230, 224, 218, 135, 147, 260]
+			}
+		]
+	}`)
+	if err != nil {
+		panic(err)
+	}
+	os.WriteFile("output.png", buf, 0600)
+}