Add gradle-specific information to docs.

docs/android_studio.md

 # Android Studio
 
 [TOC]
 
 ## Usage
 
 ```shell
 build/android/gradle/generate_gradle.py --output-directory out-gn/Debug
 ```
 
@@ skipping 72 matching lines @@
  * `Ctrl + F12`: Jump to method
  * `Ctrl + G`: Jump to line
  * `Shift + F6`: Rename variable
  * `Ctrl + Alt + O`: Organize imports
  * `Alt + Enter`: Quick Fix (use on underlined errors)
 
 ### Building from the Command Line
 
 Gradle builds can be done from the command-line after importing the project into
 Android Studio (importing into the IDE causes the Gradle wrapper to be added).
+This wrapper can also be used to invoke gradle commands.
 
     cd $GRADLE_PROJECT_DIR && bash gradlew
 
 The resulting artifacts are not terribly useful. They are missing assets,
 resources, native libraries, etc.
 
+ * Use a [gradle daemon](https://docs.gradle.org/2.14.1/userguide/gradle_daemon.html) to speed up builds:
+    * Add the line `org.gradle.daemon=true` to `~/.gradle/gradle.properties`, creating it if necessary.
+
 ## Status (as of Sept 21, 2016)
 
 ### What works
 
  * Tested with Android Studio v2.2.
  * Basic Java editing and compiling works.
 
 ### What doesn't work (yet) ([crbug](https://bugs.chromium.org/p/chromium/issues/detail?id=620034))
 
  * JUnit Test targets
- * Better support for instrumtation tests (they are treated as non-test .apks right now)
+ * Better support for instrumentation tests (they are treated as non-test .apks right now)
  * Make gradle aware of resources and assets
  * Make gradle aware of native code via pointing it at the location of our .so
  * Add a mode in which gradle is responsible for generating `R.java`
  * Add support for native code editing
  * Make the "Make Project" button work correctly