Merge pull request gulpjs#834 from danielbayerlein/gulp-watch-v3

gulp-watch v3.0.0 API

Author: Eric Schoffstall

docs/recipes/rebuild-only-files-that-change.md

@@ -9,7 +9,7 @@ var watch = require('gulp-watch');
 
 gulp.task('default', function() {
   return gulp.src('sass/*.scss')
-    .pipe(watch())
+    .pipe(watch('sass/*.scss'))
     .pipe(sass())
     .pipe(gulp.dest('dist'));
 });