Add windows build instructions for README.md in android example

I succesfully built an apk in windows but i had to adapt linux instructions to command line. So i made a .bat that should work as a template for other users.

Included some comments for the problems i noticed and also some tips for android builds

examples/others/android/example/README.md

@@ -3,6 +3,7 @@
 To compile example to shared library you will need [Android NDK](https://developer.android.com/ndk/downloads/index.html).
 To build Android apk you will need [Android SDK](http://developer.android.com/sdk/index.html#Other).
 
+## Build library on Linux
 Export path to Android NDK, point to location where you have unpacked archive:
 
     export ANDROID_NDK_HOME=/opt/android-ndk
@@ -28,10 +29,89 @@ And compile shared library:
     CGO_ENABLED=1 GOOS=android GOARCH=arm \
     go build -buildmode=c-shared -ldflags="-s -w -extldflags=-Wl,-soname,libexample.so" \
     -o=android/libs/armeabi-v7a/libexample.so
+For aarch64/arm64 replace `arm-linux-androideabi` with `aarch64-linux-android`, set GOARCH to arm64 and use minimum `ANDROID_API=21`.
+
+    
+## Build Library on Windows
+
+Save the following contents to a .bat file and place it at the root of your project. Change the top folders to match you sdk and ndk locations and then execute it from the command line or by clicking on it
+
+    @REM Set your desired api. Max is 31. Min is 21 for 64 targets
+    @set ANDROID_API=31
+    @REM Your library name. If you change it here you should also change it in your android manifest...
+    @set LIBRARY_NAME=example
+    @REM Set your android sdk folder here
+    @set ANDROID_HOME=F:/AndroidSDK 
+    @REM Set your android NDK folder here. WARNING: NDK 27 is not supported yet. See https://github.com/raysan5/raylib/issues/4166
+    @set ANDROID_NDK_HOME=F:/AndroidSDK/ndk/23.2.8568313
+    @REM The target architecture for android. See https://developer.android.com/ndk/guides/abis. 
+    @REM Valid options are: armeabi-v7a,arm64-v8a,x86,x86_64 or "all" if you want to build for all architectures.
+    @set TARGET_ARCH="all"
+    @REM Automatic setup. Should work by default. Do not change anything below here
+    @set PATH=%ANDROID_NDK_HOME%/toolchains/llvm/prebuilt/windows-x86_64/bin;%PATH%
+    @set ANDROID_SYSROOT=%ANDROID_NDK_HOME%/toolchains/llvm/prebuilt/windows-x86_64/sysroot
+    @set ANDROID_TOOLCHAIN=%ANDROID_NDK_HOME%/toolchains/llvm/prebuilt/windows-x86_64
+    @IF %TARGET_ARCH% == "all" (
+        @GOTO:BUILDALL
+    ) else (
+        @GOTO:MAIN
+    )
+    
+    :COMPILE
+            @echo compiling for platform %FL%
+            @set CGO_CFLAGS="-I%ANDROID_SYSROOT%/usr/include -I%ANDROID_SYSROOT%/usr/include/%TRIPLE% --sysroot=%ANDROID_SYSROOT% -D__ANDROID_API__=%ANDROID_API%"
+            @set CGO_LDFLAGS="-L%ANDROID_SYSROOT%/usr/lib/%TRIPLE%/%ANDROID_API% -L%ANDROID_TOOLCHAIN%/%TRIPLE%/lib --sysroot=%ANDROID_SYSROOT%"
+            @set CGO_ENABLED=1
+            @set GOOS=android
+            @set GOARCH=arm
+            @go build -buildmode=c-shared -ldflags="-s -w -extldflags=-Wl,-soname,lib%LIBRARY_NAME%.so" -o=android/libs/%FL%/lib%LIBRARY_NAME%.so
+    @EXIT /B
+    
+    :BUILDALL
+        @set TARGET_ARCH="armeabi-v7a"
+        @CALL:MAIN
+        @set TARGET_ARCH="arm64-v8a"
+        @CALL:MAIN
+        @set TARGET_ARCH="x86"
+        @CALL:MAIN
+        @set TARGET_ARCH="x86_64"
+        @CALL:MAIN
+    @EXIT /B
+    
+    :MAIN
+        @IF %TARGET_ARCH% == "armeabi-v7a" (
+            @set CC="armv7a-linux-androideabi%ANDROID_API%-clang"
+            @set TRIPLE=arm-linux-androideabi
+            @set FL=armeabi-v7a
+            @set GOARCH=arm
+            @CALL:COMPILE )
+        @IF %TARGET_ARCH% == "arm64-v8a" (
+            @set CC="armv7a-linux-androideabi%ANDROID_API%-clang"
+            @set TRIPLE=aarch64-linux-android
+            @set FL=arm64-v8a
+            @set GOARCH=arm64
+            @CALL:COMPILE )
+        @IF %TARGET_ARCH% == "x86" (
+            @set CC="armv7a-linux-androideabi%ANDROID_API%-clang"
+            @set TRIPLE=i686-linux-android
+            @set FL=x86
+            @set GOARCH=arm
+            @CALL:COMPILE )
+        @IF %TARGET_ARCH% == "x86_64" (
+            @set CC="armv7a-linux-androideabi%ANDROID_API%-clang"
+            @set TRIPLE=x86_64-linux-android
+            @set FL=x86_64
+            @set GOARCH=arm64
+            @CALL:COMPILE )
+    @EXIT /B
+
+    
+## Building the APK
 
 To build apk export path to Android SDK, point to location where you unpacked archive:
 
     export ANDROID_HOME=/opt/android-sdk
+(For windows you will need to add ANDROID_HOME to your PATH and set it's location to yout android sdk folder)
 
 And build apk:
 
@@ -39,5 +119,8 @@ And build apk:
 
 If everything is successfully built apk can be found in the android/build/outputs.
 
+## Export to distribution
 
-For aarch64/arm64 replace `arm-linux-androideabi` with `aarch64-linux-android`, set GOARCH to arm64 and use minimum `ANDROID_API=21`.
+For distribution you might want to use the bundle .aab file format, this will split the libraries when downloaded to their respective architecture on the Play Store. Smaller app size and less manual compilation
+
+Follow this link for more information: https://developer.android.com/build/building-cmdline#build_bundle