docs: improve documentation and examples for server push with Gin framework

- Change section headers to proper markdown format
- Add a new section for "Server Push" with example Go code using the Gin framework and gzip middleware

Signed-off-by: appleboy <[email protected]>

Author: appleboy

README.md

@@ -49,7 +49,7 @@ func main() {
 }
 ```
 
-Customized Excluded Extensions
+### Customized Excluded Extensions
 
 ```go
 package main
@@ -77,7 +77,7 @@ func main() {
 }
 ```
 
-Customized Excluded Paths
+### Customized Excluded Paths
 
 ```go
 package main
@@ -105,7 +105,7 @@ func main() {
 }
 ```
 
-Customized Excluded Paths
+### Customized Excluded Paths with Regex
 
 ```go
 package main
@@ -132,3 +132,38 @@ func main() {
   }
 }
 ```
+
+### Server Push
+
+```go
+package main
+
+import (
+  "fmt"
+  "log"
+  "net/http"
+  "time"
+
+  "github.com/gin-contrib/gzip"
+  "github.com/gin-gonic/gin"
+)
+
+func main() {
+  r := gin.Default()
+  r.Use(gzip.Gzip(gzip.DefaultCompression))
+  r.GET("/stream", func(c *gin.Context) {
+    c.Header("Content-Type", "text/event-stream")
+    c.Header("Connection", "keep-alive")
+    for i := 0; i < 10; i++ {
+      fmt.Fprintf(c.Writer, "id: %d\ndata: tick %d\n\n", i, time.Now().Unix())
+      c.Writer.Flush()
+      time.Sleep(1 * time.Second)
+    }
+  })
+
+  // Listen and Server in 0.0.0.0:8080
+  if err := r.Run(":8080"); err != nil {
+    log.Fatal(err)
+  }
+}
+```