Make non-libs warning less judgmental

Library/Homebrew/formula_cellar_checks.rb

@@ -69,7 +69,7 @@ module FormulaCellarChecks
 
     ["Non-libraries were installed to \"#{f.lib}\".",
       <<-EOS.undent
-        Installing non-libraries to "lib" is bad practice.
+        Installing non-libraries to "lib" is discouraged.
         The offending files are:
           #{non_libraries * "\n          "}
       EOS