[docs] Fix typo (#4201)

docs/faq.en.md

@@ -216,7 +216,7 @@ Fully customizable op, first change to one that can export (e.g. concat slice),
 
    2. [Learn in 5 minutes! Converting TorchScript models to ncnn models with PNNX](https://zhuanlan.zhihu.com/p/427512763)
 
-# 使用
+# Using
 
 - ## vkEnumeratePhysicalDevices failed -3
 
@@ -290,4 +290,4 @@ Fully customizable op, first change to one that can export (e.g. concat slice),
    ncnn::Mat in1(60, (void*)testData.data()).reshape(4, 5, 3); // just pass the pointer to the float data as a void*, and even specify the dimension (up says it's best to use reshape to solve the channel gap)
    float* a = new float[60]; // New a piece of memory yourself, you need to release it later
    ncnn::Mat in2 = ncnn::Mat(60, (void*)a).reshape(4, 5, 3).clone(); // use the same method as above, clone() to transfer data owner
-   ```
+   ```

docs/faq.md

@@ -111,7 +111,7 @@
 
 # 怎样添加ncnn库到项目中？cmake方式怎么用？
 
-编译ncnn，make install。linux/windows set/export ncnn_DIR 指向 isntall目录下下包含ncnnConfig.cmake 的目录
+编译ncnn，make install。linux/windows set/export ncnn_DIR 指向 install目录下包含ncnnConfig.cmake 的目录
 
 - ## android