Add GHDL waveform sub-section to simulato_support doc
@@ -328,6 +328,27 @@ Issues for this simulator
* `All issues with label category:simulators:ghdl <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aghdl>`_
+.. _sim-ghdl-waveforms:
+
+Waveforms
+---------
+
+To get waveforms in VCD format, set the :make:var:`SIM_ARGS` option to ``--vcd=anyname.vcd``,
+for example in a Makefile:
+
+ .. code-block:: make
+
+ SIM_ARGS=--vcd=anyname.vcd
+
+The option can be set on the command line, as shown in the following example.
+
+ .. code-block:: bash
+
+ make SIM=ghdl SIM_ARGS=--vcd=anyname.vcd
+
+A VCD file named ``anyname.vcd`` will be generated in the current directory.
+
+
.. _sim-cvc:
Tachyon DA CVC
