Add missing word from docs.

My mistaker from an earlier commit.

Change-Id: Ic04b3c411da32f7dca03d23d39182915e3567172

core/java/android/app/Service.java

@@ -403,7 +403,7 @@ public abstract class Service extends ContextWrapper implements ComponentCallbac
      *
      * <p class="caution">Note that the system calls this on your
      * service's main thread.  A service's main thread is the same
-     * thread where UI operations place for Activities running in the
+     * thread where UI operations take place for Activities running in the
      * same process.  You should always avoid stalling the main
      * thread's event loop.  When doing long-running operations,
      * network calls, or heavy disk I/O, you should kick off a new