fix some minor javadoc errors in AccountManager

     * @param account The account to fetch an auth token for

     * @param authTokenType The auth token type, an authenticator-dependent

     *     string token, must not be null

     * @param options Authenticator-specific options for the request,

     *     may be null or empty

     * @param notifyAuthFailure True to add a notification to prompt the

     *     user for a password if necessary, false to leave that to the caller

     * @param callback Callback to invoke when the request completes,

     *     null for no callback

     * @param handler {@link Handler} identifying the callback thread,

     *     null for the main thread

     * @return An {@link AccountManagerFeature} which resolves to a Bundle with

     * @return An {@link AccountManagerFuture} which resolves to a Bundle with

     *     these fields if activity was specified and an account was created:

     * <ul>

     * <li> {@link #KEY_ACCOUNT_NAME} - the name of the account created

     * {@link android.Manifest.permission#MANAGE_ACCOUNTS}.

     *

     * @param accountType The account type required

     *     (see {@link getAccountsByType}), must not be null

     *     (see {@link #getAccountsByType}), must not be null

     * @param authTokenType The desired auth token type

     *     (see {@link #getAuthToken}), must not be null

     * @param features Required features for the account