Improve package.json and add CITATION.cff

- Add keywords
- Include source template and webpack.mix.js in built package

CITATION.cff

@@ -0,0 +1,21 @@
+cff-version: 1.2.0
+title: >-
+  Visualization of project commit activity over time
+message: Please cite this software as follows.
+type: software
+authors:
+  - given-names: Leon
+    family-names: Helwerda
+    email: [email protected]
+    affiliation: Leiden University
+    orcid: 'https://orcid.org/0000-0002-4299-466X'
+  - given-names: Laurens
+    family-names: Groeneveld
+repository-code: 'https://github.com/grip-on-software/heatmap'
+repository-artifact: 'https://www.npmjs.com/package/@gros/heatmap'
+url: 'https://gros.liacs.nl/'
+keywords:
+  - visualization
+  - software-ecosystem
+license: Apache-2.0
+version: 0.0.1

package.json

@@ -2,6 +2,10 @@
   "name": "@gros/heatmap",
   "version": "0.0.1",
   "description": "Visualization of project commit activity over time.",
+  "keywords": [
+      "visualization",
+      "software-ecosystem"
+  ],
   "license": "Apache-2.0",
   "author": "Leon Helwerda <[email protected]>",
   "files": [
@@ -13,7 +17,9 @@
       "public/*.js.LICENSE.txt",
       "public/fonts/",
       "public/mix-manifest.json",
-      "res/*.scss"
+      "res/*.scss",
+      "template/*.mustache",
+      "webpack.mix.js"
   ],
   "directories": {
       "dist": "public",