Javadoc for @background annotation

https://github.com/excilys/androidannotations/pull/564/files#r4329001

Author: rom1v

AndroidAnnotations/androidannotations-api/src/main/java/org/androidannotations/annotations/Background.java

@@ -28,9 +28,26 @@
 @Retention(RetentionPolicy.CLASS)
 @Target(ElementType.METHOD)
 public @interface Background {
-	String id() default ""; /* used for task cancellation */
+	/**
+	 * Identifier for task cancellation.
+	 * 
+	 * To cancel all tasks having a specified background id:
+	 * 
+	 * <pre>
+	 * boolean mayInterruptIfRunning = true;
+	 * BackgroundExecutor.cancelAll(&quot;my_background_id&quot;, mayInterruptIfRunning);
+	 * </pre>
+	 **/
+	String id() default "";
 
-	int delay() default 0; /* in milliseconds */
+	/** Minimum delay, in milliseconds, before the background task is executed. */
+	int delay() default 0;
 
+	/**
+	 * Serial execution group.
+	 * 
+	 * All background tasks having the same <code>serial</code> will be executed
+	 * sequentially.
+	 **/
 	String serial() default "";
 }