fix(docs): fix typo and highlight keyword (#178)

demo/ncnn/android/README.md

@@ -7,17 +7,17 @@ Andoird app of YOLOX object detection base on [ncnn](https://github.com/Tencent/
 
 ### Step1
 
-Download ncnn-android-vulkan.zip from [releases of ncnn](https://github.com/Tencent/ncnn/releases). This repo us
+Download ncnn-android-vulkan.zip from [releases of ncnn](https://github.com/Tencent/ncnn/releases). This repo uses
 [20210525 release](https://github.com/Tencent/ncnn/releases/download/20210525/ncnn-20210525-android-vulkan.zip) for building.
 
 ### Step2
 
 After downloading, please extract your zip file. Then, there are two ways to finish this step:
-* put your extracted directory into app/src/main/jni
-* change the ncnn_DIR path in app/src/main/jni/CMakeLists.txt to your extracted directory.
+* put your extracted directory into **app/src/main/jni**
+* change the **ncnn_DIR** path in **app/src/main/jni/CMakeLists.txt** to your extracted directory
 
 ### Step3
-Download example param and bin file from [onedrive](https://megvii-my.sharepoint.cn/:u:/g/personal/gezheng_megvii_com/ESXBH_GSSmFMszWJ6YG2VkQB5cWDfqVWXgk0D996jH0rpQ?e=qzEqUh) or [github](https://github.com/Megvii-BaseDetection/storage/releases/download/0.0.1/yolox_s_ncnn.tar.gz). Unzip the file to app/src/main/assets.
+Download example param and bin file from [onedrive](https://megvii-my.sharepoint.cn/:u:/g/personal/gezheng_megvii_com/ESXBH_GSSmFMszWJ6YG2VkQB5cWDfqVWXgk0D996jH0rpQ?e=qzEqUh) or [github](https://github.com/Megvii-BaseDetection/storage/releases/download/0.0.1/yolox_s_ncnn.tar.gz). Unzip the file to **app/src/main/assets**.
 
 ### Step4
 Open this project with Android Studio, build it and enjoy!