coq README: give rough time estimate

1718e7be · Ralf Jung · 1b8709c9 · 1718e7be
Commit 1718e7be authored Oct 06, 2014 by Ralf Jung
--- a/README.txt
+++ b/README.txt
@@ -33,6 +33,7 @@ REQUIREMENTS
  8GB ram + 4GB swap

  We have tested the development using Coq v. 8.4pl4 on Linux and Mac machines with at least 8GB RAM + 4GB swap.
+  The entire compilation took around 3 hours.
  

 HOW TO COMPILE