Update comments for the new EXTRA_VOICE_SEARCH_RESULT_HTTP_HEADERS.

     * All the values and the keys are {@link String}s. Each key/value pair represents an extra HTTP

     * header. The keys can't be the standard HTTP headers as they are set by the WebView.

     *

     * A list of size 1 may be provided to apply the same HTTP headers to all html results. A list 

     * of the same size as {@link #EXTRA_VOICE_SEARCH_RESULT_STRINGS} may be provided to apply 

     * different HTTP headers to each different html result in the 

     * {@link #EXTRA_VOICE_SEARCH_RESULT_HTML} list.

     * A list of size 1 may be provided to apply the same HTTP headers to all web results. A

     * list of the same size as {@link #EXTRA_VOICE_SEARCH_RESULT_STRINGS} may be provided to

     * apply different HTTP headers to each different web result in the list. These headers will

     * only be used in the case that the url for a particular web result (from

     * {@link #EXTRA_VOICE_SEARCH_RESULT_URLS}) is loaded.

     *

     * @hide not to be exposed immediately as the implementation details may change

     */