chore: add some annotations (#1544)

ref: #1075 
because I am not a native English, maybe have a bit problem.

examples/basic/main.go

@@ -6,7 +6,7 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-var DB = make(map[string]string)
+var db = make(map[string]string)
 
 func setupRouter() *gin.Engine {
 	// Disable Console Color
@@ -21,7 +21,7 @@ func setupRouter() *gin.Engine {
 	// Get user value
 	r.GET("/user/:name", func(c *gin.Context) {
 		user := c.Params.ByName("name")
-		value, ok := DB[user]
+		value, ok := db[user]
 		if ok {
 			c.JSON(http.StatusOK, gin.H{"user": user, "value": value})
 		} else {
@@ -50,7 +50,7 @@ func setupRouter() *gin.Engine {
 		}
 
 		if c.Bind(&json) == nil {
-			DB[user] = json.Value
+			db[user] = json.Value
 			c.JSON(http.StatusOK, gin.H{"status": "ok"})
 		}
 	})