Update README.md

mark-i-m · web-flow · commit dc037e216bf4 · 2018-02-04T16:11:19.000-06:00
diff --git a/README.md b/README.md
@@ -33,3 +33,5 @@ be found.
 ```
 $ cargo install mdbook-linkcheck
 ```
+You will need `mdbook` version `>= 0.1`. `linkcheck` will be run automatically
+when you run `mdbook build`.
