gulpfile.js
function startWatch() {
  var rp = path.join(rootPath, '/**/*.md')
  watcher = gulp.watch([rp, '!' + rp + '/_book/'], function() {
    rebuildBook(reload)
  })
  return watcher
}
function startWatch() {
  var rp = path.join(rootPath, '/**/*.md')
  watcher = gulp.watch([rp, '!' + rp + '/_book/'], function() {
    rebuildBook(reload)
  })
  return watcher
}
function startWatch ( ) { var rp = path . join ( rootPath , '/**/*.md' ) watcher = gulp . watch ( [ rp , '!' + rp + '/_book/' ] , function ( ) { rebuildBook ( reload ) } ) return watcher }
start watching md files + when files changed reload browser
start watching md files + when files changed reload browser