Clarify upgrade path
Clarify upgrade path

Fixes #374

derby-developers/teaspoon,beni55/teaspoon,andresbravog/teaspoon,derby-developers/teaspoon,iainbeeston/teaspoon,bouk/teaspoon,derby-developers/teaspoon,iainbeeston/teaspoon,andresbravog/teaspoon,beni55/teaspoon,modeset/teaspoon,andresbravog/teaspoon,modeset/teaspoon,beni55/teaspoon,bouk/teaspoon,iainbeeston/teaspoon,bouk/teaspoon,modeset/teaspoon