Fix react link (#3667)

docs/source/developer/virtualdom.rst

@@ -12,7 +12,7 @@ In situations where these feature are needed, we recommend using
 Phosphor's ``Widget`` class directly.
 
 The idea of virtual DOM rendering, which became popular in the
-`React <https://nodejs.org/en/>`__ community, is a very elegant and
+`React <https://reactjs.org/>`__ community, is a very elegant and
 efficient way of rendering and updating DOM content in response to
 model/state changes.