Update Icarus Verilog link to cocotb's simulator support page
@@ -18,7 +18,7 @@ Cocotb requires:
- Python 3.5+
- A C++11 compiler
-- An HDL simulator (such as [Icarus Verilog](http://iverilog.icarus.com/),
+- An HDL simulator (such as [Icarus Verilog](https://docs.cocotb.org/en/stable/simulator_support.html#icarus-verilog),
[Verilator](https://docs.cocotb.org/en/stable/simulator_support.html#verilator),
[GHDL](https://docs.cocotb.org/en/stable/simulator_support.html#ghdl) or
[other simulator](https://docs.cocotb.org/en/stable/simulator_support.html))
