remove map(Match::toString) from javadoc

Author: fluentfuture

mug/src/main/java/com/google/mu/util/Substring.java

@@ -720,7 +720,6 @@ public final BiOptional<String, String> split(CharSequence string) {
      * String toSplit = " x -> y, z-> a, x -> t ";
      * ImmutableListMultimap<String, String> result = first(',')
      *     .delimit(toSplit)
-     *     .map(Match::toString)
      *     .map(first("->")::splitThenTrim)
      *     .collect(concatenating(BiOptional::stream))  // Or use BiStream.concat()
      *     .collect(ImmutableListMultimap::toImmutableListMultimap);