docs: add createInstance desc (module-federation#4509)

Author: 2heal1

apps/website-new/docs/en/guide/runtime/runtime-api.mdx

@@ -12,13 +12,15 @@ Used to create ModuleFederation instance.
 
 * When to use `createInstance`?
 
-To ensure the uniqueness of the ModuleFederation instance, after the build plugin creates an instance, it will be stored in memory. The exported APIs all first obtain the ModuleFederation instance from memory and then call the APIs of the ModuleFederation instance. This is also why APIs like loadRemote can be used directly from the `@module-federation/enhanced/runtime` package and inherently understand what application container they are attached to.
+  To ensure the uniqueness of the ModuleFederation instance, after the build plugin creates an instance, it will be stored in memory. The exported APIs all first obtain the ModuleFederation instance from memory and then call the APIs of the ModuleFederation instance. This is also why APIs like loadRemote can be used directly from the `@module-federation/enhanced/runtime` package and inherently understand what application container they are attached to.
 
-This singleton pattern works for most scenarios, but in the following cases, you need to use `createInstance`:
+  This singleton pattern works for most scenarios, but in the following cases, you need to use `createInstance`:
 
-- No build plugin is used  (Only use runtime)
-- Multiple ModuleFederation instances need to be created with different configurations for each instance
-- You want to use ModuleFederation's partitioning feature to encapsulate corresponding APIs for use in other projects
+  - No build plugin is used  (Only use runtime)
+  - Multiple ModuleFederation instances need to be created with different configurations for each instance
+  - You want to use ModuleFederation's partitioning feature to encapsulate corresponding APIs for use in other projects
+
+* `createInstance` will not overwrite an existing instance. Each call will create a new instance.
 
 ```ts
 import { createInstance } from '@module-federation/enhanced/runtime';

apps/website-new/docs/zh/guide/runtime/runtime-api.mdx

@@ -12,13 +12,16 @@ import Runtime from '@components/zh/runtime/index';
 
 * 什么时候使用 `createInstance` ？
 
-为了保证 `ModuleFederation` 实例的唯一性，我们在构建插件创建实例后，会将其存储到内存中，导出的 API 都是先从内存中获取 `ModuleFederation` 实例，然后再调用 `ModuleFederation` 实例的 API。这也是为什么 `loadRemote` 等 API 可以直接使用的原因。
+  为了保证 `ModuleFederation` 实例的唯一性，我们在构建插件创建实例后，会将其存储到内存中，导出的 API 都是先从内存中获取 `ModuleFederation` 实例，然后再调用 `ModuleFederation` 实例的 API。这也是为什么 `loadRemote` 等 API 可以直接使用的原因。
 
-这种单例模式适用于大多数场景，但如果在以下场景，你需要使用 `createInstance`：
+  这种单例模式适用于大多数场景，但如果在以下场景，你需要使用 `createInstance`：
 
-- 没有使用构建插件（纯运行时场景）
-- 需要创建多个 ModuleFederation 实例，每个实例的配置不同
-- 希望使用 ModuleFederation 分治特性，封装相应的 API 提供给其他项目使用
+  - 没有使用构建插件（纯运行时场景）
+  - 需要创建多个 ModuleFederation 实例，每个实例的配置不同
+  - 希望使用 ModuleFederation 分治特性，封装相应的 API 提供给其他项目使用
+
+
+* `createInstance` 不会对已存在的实例进行覆盖，每次调用都会创建一个新的实例。
 
 ```ts
 import { createInstance } from '@module-federation/enhanced/runtime';