Add NDK HOME ENV (#28)

Signed-off-by: gengjiawen <[email protected]>

Author: gengjiawen

Dockerfile

@@ -1,7 +1,6 @@
 FROM openjdk:8-slim
 
 LABEL Description="This image provides a base Android development environment for React Native, and may be used to run tests."
-LABEL maintainer="Héctor Ramos <[email protected]>"
 
 # set default build arguments
 ARG SDK_VERSION=sdk-tools-linux-3859397.zip
@@ -18,6 +17,7 @@ ENV ANDROID_HOME=/opt/android
 ENV ANDROID_SDK_HOME=${ANDROID_HOME}
 ENV PATH=${PATH}:${ANDROID_HOME}/tools:${ANDROID_HOME}/tools/bin:${ANDROID_HOME}/platform-tools
 ENV ANDROID_NDK=/opt/ndk/android-ndk-r$NDK_VERSION
+ENV ANDROID_NDK_HOME=/opt/ndk/android-ndk-r$NDK_VERSION
 ENV PATH=${PATH}:${ANDROID_NDK}
 
 # install system dependencies