Referencing the original issue as per Michael's request

SkyWriter · SkyWriter · commit d7293f4b0dbb · 2018-05-23T00:34:51.000+06:00
diff --git a/src/Stack/Build/ConstructPlan.hs b/src/Stack/Build/ConstructPlan.hs
@@ -187,7 +187,7 @@ constructPlan ls0 baseConfigOpts0 locals extraToBuild0 localDumpPkgs loadPackage
 
     bconfig <- view buildConfigL
     when (hasBaseInDeps bconfig) $
-      prettyWarn $ flow "You are trying to upgrade/downgrade base, which is almost certainly not what you really want. Please, consider using another GHC version if you need a certain version of base, or removing base from extra-deps." <> line
+      prettyWarn $ flow "You are trying to upgrade/downgrade base, which is almost certainly not what you really want. Please, consider using another GHC version if you need a certain version of base, or removing base from extra-deps. See more at https://github.com/commercialhaskell/stack/issues/3940." <> line
 
     econfig <- view envConfigL
     let onWanted = void . addDep False . packageName . lpPackage
