ReadMe: Instructions on how to update submodules.

ReadMe.md

@@ -56,9 +56,20 @@ Once you have an access token, create a [`DbxClientV2`](https://dropbox.github.i
 
 You only need to perform the authorization process once per user.  Once you have an access token for a user, save it somewhere persistent, like in a database.  The next time that user visits your app's, you can skip the authorization process and go straight to creating a `DbxClientV2` and making API calls.
 
+## Building from source
+
+```
+git clone https://github.com/dropbox/dropbox-sdk-java.git
+cd dropbox-sdk-java
+./update-submodules    # also do this after every "git checkout"
+./gradlew build
+```
+
+The output will be in "build/".
+
 ## Running the examples
 
-1. Download this repository.
+1. Follow the instructions in the "Build from source" section above.
 2. Save your Dropbox API key in a file called "test.app".  See: [Get a Dropbox API key](#get-a-dropbox-api-key), above.
 3. Compile and install the SDK into your local maven repo: `./gradlew install`
 4. To compile all the examples: `(cd examples/ && ./gradlew classes`
@@ -168,4 +179,4 @@ Versions 2.0.0-2.0.3 of this SDK require SDK-specific ProGuard rules when shrink
 -dontwarn javax.servlet.**
 ```
 
-**IMPORTANT: If you are running version 2.0.x before 2.0.3, you should update to the latest Dropbox SDK version to avoid a deserialization bug that can cause Android apps that use ProGuard to crash.**
+**IMPORTANT: If you are running version 2.0.x before 2.0.3, you should update to the latest Dropbox SDK version to avoid a deserialization bug that can cause Android apps that use ProGuard to crash.**

update-submodules

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+git submodule sync
+git submodule update --init
+git submodule foreach --recursive "git submodule sync ; git submodule update --init"