Minor instruction update.

darrenjs · web-flow · commit 7a92e0d08962 · 2020-03-17T22:59:55.000Z
diff --git a/README.md b/README.md
@@ -35,6 +35,8 @@ Or on MacOS:
 
 Or just try the makefile, for Linux platforms.
 
+On Ubuntu systems you may need to run `sudo apt install libssl-dev` to install OpenSSL headers.
+
 Running
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