Add engines to make the minimum required Node version more clear

Author: MichaelDeBoey

.travis.yml

@@ -1,7 +1,7 @@
 language: node_js
 node_js:
-  # eslint 7: node 10+
-  # jest 26: node 10+
+  # eslint 7: node 10.12+
+  # jest 26: node 10.14.2+
   - 14
   - 12
   - 10
@@ -14,7 +14,7 @@ env:
   - 'ESLINT=6 JEST=26'
   - 'ESLINT=7 JEST=26'
 matrix:
-  # jest 25: 8+
+  # jest 25: node 8+
   include:
     # eslint 6, node 8
     - node_js: 8

package.json

@@ -54,5 +54,8 @@
     "proseWrap": "never",
     "singleQuote": true,
     "trailingComma": "all"
+  },
+  "engines": {
+    "node": ">=8.10.0"
   }
 }