docs: intro updated

Author: rodrigomelo9

docs/intro.rst

@@ -1,10 +1,31 @@
 Introduction
 ============
 
-HDL converter (between VHDL, SystemVerilog and/or Verilog), based on `GHDL <https://github.com/ghdl/ghdl>`_, `Yosys <https://github.com/YosysHQ/yosys>`_, `Synlig <https://github.com/chipsalliance/synlig>`_ and the plugins `ghdl-yosys-plugin <https://github.com/ghdl/ghdl-yosys-plugin>`_ and `yosys-slang <https://github.com/povik/yosys-slang>`_.
+HDL converter provides a set of command-line utilities for converting between VHDL, SystemVerilog, and Verilog.
+Those, gathers files and options, then orchestrates the execution of the following tools - either separately or in combination when required.
 
-It relies on `Docker <https://docs.docker.com/get-docker>`_ and `PyFPGA containers <https://github.com/PyFPGA/containers>`_.
+* `GHDL <https://github.com/ghdl/ghdl>`_
+* `Yosys <https://github.com/YosysHQ/yosys>`_
+* `Synlig <https://github.com/chipsalliance/synlig>`_
+* `ghdl-yosys-plugin <https://github.com/ghdl/ghdl-yosys-plugin>`_
+* `yosys-slang <https://github.com/povik/yosys-slang>`_
 
-* ``vhdl2vhdl``: converts from a newer VHDL to VHDL'93 (using ``ghdl``).
-* ``vhdl2vlog``: converts from VHDL to Verilog (backends: ``ghdl`` or ``yosys``).
-* ``slog2vlog``: converts from SystemVerilog to Verilog (frontends: ``slang``, ``synlig`` or ``yosys``).
+To avoid the need to install multiple tools, it relies on `Docker <https://docs.docker.com/get-docker>`_ and `PyFPGA containers <https://github.com/PyFPGA/containers>`_.
+
+Command-line utilities
+----------------------
+
+* ``vhdl2vhdl``: converts from a newer VHDL to VHDL'93.
+    * Solved using ``ghdl``.
+* ``vhdl2vlog``: converts from VHDL to Verilog.
+        * This has two alternatives:
+        * Purely ``ghdl`` (default).
+        * ``ghdl-yosys-plugin`` as frontend and ``yosys`` as backend.
+* ``slog2vlog``: converts from SystemVerilog to Verilog.
+    * This has three alternatives:
+        * ``yosys-slang`` as frontend and ``yosys`` as backend (default).
+        * Purely ``synlig`` (based on ``Surelog`` and ``yosys``).
+        * Purely ``yosys`` (simpler SV support, but could be sufficient in some cases).
+
+.. note::
+   Multiple alternatives are provided so you can try different options if one does not work.