README: link directly to Yosys build instructions.

diff --git a/README.md b/README.md
index 280ba1ba11c41531e531b65947bde406ebd162f8..45e4bd60a303d165f5a3bafb3f891756d631d1df 100644 (file)
--- a/README.md
+++ b/README.md
@@ -26,9 +26,13 @@ The development of nMigen has been supported by [SymbioticEDA][], [LambdaConcept
 
 nMigen requires Python 3.6 (or newer), [Yosys][] 0.9 (or newer), as well as a device-specific toolchain.
 
+First, install Yosys, either using your system package manager, or [from source][yosyssrc]. Then, install nMigen and pinouts for many common FPGA developer boards:
+
     pip install git+https://github.com/nmigen/nmigen.git
     pip install git+https://github.com/nmigen/nmigen-boards.git
 
+[yosyssrc]: https://github.com/yosysHQ/yosys/#setup
+
 ### Introduction
 
 TBD