Add remaining haskell book exercises

Haskell-book/18/Instance/package.yaml

@@ -0,0 +1,26 @@
+name:                Instance
+version:             0.1.0.0
+github:              "githubuser/Instance"
+license:             BSD3
+author:              "Eugen Wissner"
+maintainer:          "belka@caraus.de"
+copyright:           "2018 Eugen Wissner"
+
+dependencies:
+- base >= 4.7 && < 5
+- QuickCheck
+- checkers
+
+library:
+  source-dirs: src
+
+tests:
+  Instance-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - Instance