Update README.md

README.md

@@ -117,6 +117,12 @@
 - Apple OSX(Darwin), both 32 and 64bits.
 - All hardware with x86/x86_64/arm/mips cpu.
 - Windows.
+
+## How to build
+
+It is recommended to compile on Ubuntu or MacOS，compiling on windows is cumbersome, and some features are not compiled by default.
+
+### Before build
 - **You must use git to clone the complete code. Do not download the source code by downloading zip package. Otherwise, the sub-module code will not be downloaded by default.You can do it like this:**
 ```
 git clone https://github.com/zlmediakit/ZLMediaKit.git
@@ -124,12 +130,6 @@ cd ZLMediaKit
 git submodule update --init
 ```
 
-
-
-## How to build
-
-It is recommended to compile on Ubuntu or MacOS，compiling on windows is cumbersome, and some features are not compiled by default.
-
 ### Build on linux
 
 - My environment