Remove documentation about "pub run test:test".

test/runner/runner_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 @TestOn("vm")
 
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:scheduled_test/descriptor.dart' as d;
@@ skipping 24 matching lines @@
 """;
 
 final _defaultConcurrency = math.max(1, Platform.numberOfProcessors ~/ 2);
 
 final _browsers =
     "[vm (default), dartium, content-shell, chrome, phantomjs, firefox" +
         (Platform.isMacOS ? ", safari" : "") +
         (Platform.isWindows ? ", ie" : "") + "]";
 
 final _usage = """
-Usage: pub run test:test [files or directories...]
+Usage: pub run test [files or directories...]
 
 -h, --help                     Shows this usage information.
     --version                  Shows the package's version.
 
 ======== Selecting Tests
 -n, --name                     A substring of the name of the test to run.
                                Regular expression syntax is supported.
                                If passed multiple times, tests must match all substrings.
 
 -N, --plain-name               A plain-text substring of the name of the test to run.
@@ skipping 508 matching lines @@
   });
 
   test("with the --color flag, uses colors", () {
     d.file("test.dart", _failure).create();
     var test = runTest(["--color", "test.dart"]);
     // This is the color code for red.
     test.stdout.expect(consumeThrough(contains("\u001b[31m")));
     test.shouldExit();
   });
 }