zdifftool README

1. confirm first text/url
   1. by select and apply command zdifftool:diffwithSelection1与待比较文本直接比较
   2. by ctrl/cmd + c
2. confirm second text/url to diff
   1. by select next text
3. apply diff command
   1. by run zdifftool:diffwithSelection1与待比较文本直接比较 or zdifftool:diffQSwithSelection1与待比较文本进行url参数比较
   2. or by run zdifftool:diffWithClipboard与粘贴板文本直接比较 or zdifftool:diffQSWithClipboard与粘贴板文本进行url参数比较