When I first read up on lexical binding, I didn't realize that I also
needed to review the documentation for dynamic binding, so that I
could learn about special variables.  I think it would be good for the
Info page for lexical binding to mention special variables, clarify
that the specialness also affects new bindings (not just the initial
defvar/defcustom/defconst), and provide a link to the page for dynamic
binding (for details about special variables).

I've enclosed a draft patch for your consideration.

thanks,
mike