updated 'document-env-vars' version, added documentation for env var 'ORIGIN'

README.md

@@ -41,6 +41,10 @@ URL to your local Pulse API instance (if you have one set up). e.g., `PULSE_API=
 
 To set up a local instance of Pulse API, follow instructions on https://github.com/mozilla/network-pulse-api/blob/master/README.md.
 
+#### `ORIGIN` (auto-generated)
+
+Derived variable based on `HOST` and `PORT` - overriding this yourself will do nothing.
+
 ## 🔷 More info
 
  - [Research doc](https://docs.google.com/document/d/1SAAuPgOaVqpQorrbD0vZSnf8wHHYjddPyYrkrFj72kQ/)

package.json

@@ -50,7 +50,7 @@
   "devDependencies": {
     "chokidar": "^1.6.1",
     "chokidar-cli": "^1.2.0",
-    "document-env-vars": "^2.0.0",
+    "document-env-vars": "^2.1.0",
     "eslint": "^3.11.1",
     "eslint-plugin-react": "^6.7.1",
     "mofo-style": "^2.4.0",