!18401 Change colon to equal sign, fix spelling errors

Merge pull request !18401 from Li Yuhang/fix_description_0519

en/application-dev/media/using-avsession-developer.md

@@ -88,7 +88,7 @@ To enable an audio and video application to access the AVSession service as a pr
    ```ts
    // It is assumed that an AVSession object has been created. For details about how to create an AVSession object, see the node snippet above.
    let session: AVSessionManager.AVSession = ALLREADY_CREATE_A_SESSION;
-   let wantAgentInfo: {
+   let wantAgentInfo = {
        wants: [
            {
                bundleName: "com.example.musicdemo",

zh-cn/application-dev/media/using-avsession-developer.md

@@ -143,7 +143,7 @@
    ```ts
    // 假设已经创建了一个session，如何创建session可以参考之前的案例
    let session: AVSessionManager.AVSession = ALREADY_CREATE_A_SESSION;
-   let wantAgentInfo: {
+   let wantAgentInfo = {
        wants: [
            {
                bundleName: 'com.example.musicdemo',