docs: update development of go sdk and server details. (#252)

* feat: add doc about second development of server.

* docs: update development of go sdk and server details.

* docs: update development of go sdk and server details.

* docs: update development of go sdk and server details.

* docs: update development of go sdk and server details.

Author: FGadvancer

docs/guides/solution/developNewFeatures.mdx

@@ -339,15 +339,6 @@ func (r *Relation) AddFriendCategory(ctx context.Context, req *relation.AddFrien
 }
 ```
 
-将这个接口定义到 `open_im_sdk/relation.go` 中，以便下游 SDK 调用。
-
-```go
-func AddFriendCategory(callback open_im_sdk_callback.Base, operationID string, req string){
-  call(callback, operationID, UserForSDK.Relation().AddFriendCategory, req)
-}
-在相应模块的 `api.go` 中定义对应的方法，如：
-```
-
 ## 2、实现 SDK 接口业务逻辑
 
 我们需要在 `internal/relation/api.go` 中实现对应的逻辑方法：