7066490: @since 1.7 tag is missing for java.util.regex.Matcher.group(java.lang.String)

Added the @since 1.7 tag

Reviewed-by: mduigou, forax

jdk/src/share/classes/java/util/regex/Matcher.java

@@ -515,6 +515,7 @@ public final class Matcher implements MatchResult {
      * @throws  IllegalArgumentException
      *          If there is no capturing group in the pattern
      *          with the given name
+     * @since 1.7
      */
     public String group(String name) {
         if (name == null)