rework build directions

README.md

@@ -61,22 +61,12 @@ Building
 --------
 
 To generate the build scripts provision a cabal sandbox with pandoc in it. This
-is done by the ``write-you-a-haskell.cabal`` file.
-
-**Cabal**
-
-```bash
-$ cabal sandbox init
-$ cabal install --only-dependencies
-$ cabal exec bash
-$ make
-```
+is done by the ``write-you-a-haskell.cabal`` and  ``stack.yaml`` files.
 
 **Stack**
 
 ```bash
-$ stack exec bash
-$ make
+$ stack exec make
 ```
 
 To make the generate the pdf, the LaTeX packages must be installed on the
@@ -89,6 +79,15 @@ $ sudo tlmgr install zapfding
 $ stack exec make pdf
 ```
 
+**Cabal**
+
+```bash
+$ cabal sandbox init
+$ cabal install --only-dependencies
+$ cabal exec bash
+$ make
+```
+
 Contributing
 ------------