Add Java and Android SDK upgrade instructions

docs/howtos/upgrades/android.md

@@ -0,0 +1,47 @@
+# Java
+
+Our Java version should be kept in sync with the version Firefox Android is using.
+Update the version number in:
+
+- `docs/building.md`
+- `libs/verify-android-ci-environment.sh`
+- `taskcluster/docker/linux/Dockerfile`
+
+
+# Android SDK (Software Development Kit)
+
+The Android SDK is a set of development tools for building Android Apps.
+
+## Compile version
+
+This specifies what we use to build our code.
+Keep this in sync with the version Firefox Android is using.
+Update the version number in:
+
+* `build.gradle`
+* `taskcluster/docker/linux/Dockerfile`
+
+## Target / minimum versions
+
+These control which devices the library is compatible with and control which version-specific features are enabled.
+Keep this in sync with the version Firefox Android is using.
+Update the version number in:
+
+* `build.gradle`
+
+# Android NDK (Native Development Kit)
+
+The Android NDK is the toolset we use for cross-compiling our Rust code so that Firefox Android can dynamically link to it.
+
+* Update the version number in:
+  * `build.gradle` (search for `ndkVersion`)
+  * `taskcluster/docker/linux/Dockerfile` (search for `ANDROID_NDK_VERSION`)
+  * `components/support/rc_crypto/nss/nss_build_common/src/lib.rs` (search for `ANDROID_NDK_VERSION`)
+* Update these docs by replacing the old version with the new one:
+  * docs/building.md
+  * docs/howtos/locally-building-jna.md
+* These may need updating if the directory structure changed between this version and the last
+  * `libs/build-android-common.sh`: ensure the paths to the various binaries are correct.
+  * `components/support/rc_crypto/nss/nss_build_common/src/lib.rs`: search for
+    `DARWIN_X86_64_LIB_DIR` and `LINUX_X86_64_LIB_DIR`, and ensure that both point to the correct lib directory containing
+    `libclang_rt.builtins-x86_64-android.a`.