Fixed typos for comments (#6453)

* Update Maybe.java

* Update Single.java

Author: lxsmnsyc

src/main/java/io/reactivex/Maybe.java

@@ -3685,7 +3685,7 @@ public final Single<T> toSingle() {
      *  <dt><b>Scheduler:</b></dt>
      *  <dd>{@code onErrorComplete} does not operate by default on a particular {@link Scheduler}.</dd>
      * </dl>
-     * @return the new Completable instance
+     * @return the new Maybe instance
      */
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
@@ -3702,7 +3702,7 @@ public final Maybe<T> onErrorComplete() {
      * </dl>
      * @param predicate the predicate to call when an Throwable is emitted which should return true
      * if the Throwable should be swallowed and replaced with an onComplete.
-     * @return the new Completable instance
+     * @return the new Maybe instance
      */
     @CheckReturnValue
     @NonNull
@@ -3984,7 +3984,7 @@ public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? e
      *  <dd>{@code retry} does not operate by default on a particular {@link Scheduler}.</dd>
      * </dl>
      *
-     * @return the nww Maybe instance
+     * @return the new Maybe instance
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */
     @CheckReturnValue
@@ -4006,7 +4006,7 @@ public final Maybe<T> retry() {
      * @param predicate
      *            the predicate that determines if a resubscription may happen in case of a specific exception
      *            and retry count
-     * @return the nww Maybe instance
+     * @return the new Maybe instance
      * @see #retry()
      * @see <a href="http://reactivex.io/documentation/operators/retry.html">ReactiveX operators documentation: Retry</a>
      */

src/main/java/io/reactivex/Single.java

@@ -476,7 +476,7 @@ public static <T> Flowable<T> concatEager(Iterable<? extends SingleSource<? exte
     }
 
     /**
-     * Provides an API (via a cold Completable) that bridges the reactive world with the callback-style world.
+     * Provides an API (via a cold Single) that bridges the reactive world with the callback-style world.
      * <p>
      * <img width="640" height="454" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Single.create.png" alt="">
      * <p>