add readme.md

this contains build instructions on how to build this project

readme.md

@@ -0,0 +1,37 @@
+## build instructions
+
+* install gomobile
+
+```bash
+go install golang.org/x/mobile/cmd/gomobile@latest
+```
+
+* build yggdrasil-go for android:
+
+```
+git clone https://github.com/yggdrasil-network/yggdrasil-go /tmp/yggdrasil-go
+cd /tmp/yggdrasil-go
+./contrib/mobile/build -a
+```
+
+* clone yggdrasil for android and copy over the built go library
+
+```
+git clone https://github.com/yggdrasil-network/yggdrasil-android /tmp/yggdrasil-android
+mkdir /tmp/yggdrasil-android/app/libs
+cp /tmp/yggdrasil-go/yggdrasil.aar /tmp/yggdrasil-android/app/libs/
+```
+
+* build yggdrasil-android
+
+```
+cd /tmp/yggdrasil-android
+./gradew assemble
+```
+
+note: you will need to use jdk-11 as jdk-16 `"doesn't work" ™`
+
+on debian/ubuntu you can set which jdk used with the `JAVA_HOME` env var:
+```
+export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64/
+```