docs/install: link to playground.

Author: whitequark

docs/install.rst

@@ -1,6 +1,20 @@
 Installation
 ############
 
+.. _install-playground:
+
+In-browser playground
+=====================
+
+You can try Amaranth out without installing anything by visiting the `Amaranth Playground`_. The playground webpage contains a `fully functional Python interpreter <Pyodide_>`_ and an Amaranth toolchain that can simulate a design, display waveforms, and generate Verilog code. It works on all modern browsers that support WebAssembly_, including Firefox, Chrome, and Edge.
+
+.. _Amaranth Playground: https://amaranth-lang.org/play/
+.. _Pyodide: https://pyodide.org/en/stable/
+.. _WebAssembly: https://webassembly.org/
+
+
+.. _install-sysreqs:
+
 System requirements
 ===================
 
@@ -11,9 +25,9 @@ System requirements
 
 Amaranth HDL requires Python 3.8; it works on CPython_ 3.8 (or newer), and works faster on PyPy3.8_ 7.3.7 (or newer). Installation requires pip_ 23.0 (or newer).
 
-For most workflows, Amaranth requires Yosys_ |yosys-version|. A compatible version of Yosys is distributed via PyPI_ for most popular platforms.
+For most workflows, Amaranth requires Yosys_ |yosys-version|. A `compatible version of Yosys <amaranth-yosys_>`_ is distributed via PyPI_ for most popular platforms, so it is usually not necessary to install Yosys separately.
 
-Simulating Amaranth code requires no additional software. However, a waveform viewer like GTKWave_ is invaluable for debugging.
+Simulating Amaranth code requires no additional software. However, a waveform viewer like GTKWave_ is invaluable for debugging. As an alternative to GTKWave, the `Amaranth Playground`_ can be used to display waveforms for simple designs.
 
 Synthesizing, placing and routing an Amaranth design for an FPGA requires the FPGA family specific toolchain.
 
@@ -23,6 +37,7 @@ Synthesizing, placing and routing an Amaranth design for an FPGA requires the FP
 .. _PyPy3.8: https://www.pypy.org/
 .. _pip: https://pip.pypa.io/en/stable/
 .. _Yosys: https://yosyshq.net/yosys/
+.. _amaranth-yosys: https://pypi.org/project/amaranth-yosys/
 .. _PyPI: https://pypi.org/
 .. _GTKWave: https://gtkwave.sourceforge.net/
 
@@ -120,6 +135,7 @@ Installing prerequisites
 
          $ pip3 install --user --upgrade pip
 
+
 .. _install:
 
 Installing Amaranth