Just Do This
I had the same problem in MonoDevalop, but the url in it cannot be changed. So I tried a plugin of Chrome :https://chrome.google.com/webstore/detail/redirector/pajiegeliagebegjdhebejdlknciafen
We can set the transform in options of this plugin.
From:
^https://unity3d.com/cn/support/documentation/ScriptReference/(.*)
To:
https://docs.unity3d.com/ScriptReference/$1

Then we can use Ctrl + ' to search in the documentation.