docs: fix taos_init() return type (#22475)

docs/en/14-reference/03-connector/03-cpp.mdx

@@ -135,7 +135,7 @@ The following describes the basic API, synchronous API, asynchronous API, subscr
 
 The base API is used to do things like create database connections and provide a runtime environment for the execution of other APIs.
 
-- `void taos_init()`
+- `int taos_init()`
 
   Initializes the runtime environment. If the API is not actively called, the driver will automatically call the API when `taos_connect()` is called, so the program generally does not need to call it manually.
 

docs/zh/08-connector/10-cpp.mdx

@@ -223,7 +223,7 @@ int taos_print_row(char *str, TAOS_ROW row, TAOS_FIELD *fields, int num_fields)
 
 基础 API 用于完成创建数据库连接等工作，为其它 API 的执行提供运行时环境。
 
-- `void taos_init()`
+- `int taos_init()`
 
   初始化运行环境。如果没有主动调用该 API，那么调用 `taos_connect()` 时驱动将自动调用该 API，故程序一般无需手动调用。