fix code example typo for topic in ydb go sdk (#9894)

Author: rekby

ydb/docs/en/core/reference/ydb-sdk/topic.md

@@ -485,7 +485,7 @@ Only connections with matching [producer and message group](../../concepts/topic
      topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
      topicwriter.Message{Data: strings.NewReader("3")},
    )
-   if err == nil {
+   if err != nil {
      return err
    }
    ```
@@ -621,7 +621,7 @@ Only connections with matching [producer and message group](../../concepts/topic
     topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
     topicwriter.Message{Data: strings.NewReader("3")},
   )
-  if err == nil {
+  if err != nil {
     return err
   }
   ```

ydb/docs/ru/core/reference/ydb-sdk/topic.md

@@ -493,7 +493,7 @@
     topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
     topicwriter.Message{Data: strings.NewReader("3")},
   )
-  if err == nil {
+  if err != nil {
     return err
   }
   ```
@@ -628,7 +628,7 @@
     topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
     topicwriter.Message{Data: strings.NewReader("3")},
   )
-  if err == nil {
+  if err != nil {
     return err
   }
   ```