Fixed: Updated elm.json file

The elm.json file was copied from another project. This fixes it by adding information for the current project.

Author: ahankinson

elm.json

@@ -1,7 +1,7 @@
 {
     "type": "package",
-    "name": "gampleman/elm-rosetree",
-    "summary": "Strict multiway trees aka rosetrees and a Zipper to go with them",
+    "name": "gampleman/core-extra",
+    "summary": "This is a collection of utility functions that provide additional or improved functions to the Elm standard library.",
     "license": "BSD-3-Clause",
     "version": "1.0.0",
     "exposed-modules": [