Add a little documentation inside .env.defaults

.env.defaults

-# This origin trial token is used to enable WebVR and Gamepad Extensions on Chrome 62+
-# You can find more information about getting your own origin trial token here: https://github.com/GoogleChrome/OriginTrials/blob/gh-pages/developer-guide.md
-ORIGIN_TRIAL_TOKEN="AmTuFlYFGJ4KEbPVE20U0qoWZI3NZuaO8bjjcQvQI4OvDVC4Iyun5gkD8lwtNbrEzh617m5nig0+8QC+Pz6powYAAABVeyJvcmlnaW4iOiJodHRwczovL2h1YnMubW96aWxsYS5jb206NDQzIiwiZmVhdHVyZSI6IldlYlZSMS4xTTYyIiwiZXhwaXJ5IjoxNTM0ODg3ODE1fQ=="
-ORIGIN_TRIAL_EXPIRES="2018-08-21"
+# To override these variables, create a .env file containing the overrides.
+
+# The Janus backend to connect to. Used for all WebRTC traffic (realtime audio and networked data.)
+# See here for the server code: https://github.com/mozilla/janus-plugin-sfu
 JANUS_SERVER="wss://dev-janus.reticulum.io"
+
+# The Reticulum backend to connect to. Used for storing information about active hubs.
+# See here for the server code: https://github.com/mozilla/reticulum
 RETICULUM_SERVER="dev.reticulum.io"
+
+# The root URL under which Hubs expects environment GLTF bundles to be served.
 ASSET_BUNDLE_SERVER="https://asset-bundles-prod.reticulum.io"
+
+# The root URL under which Hubs expects static assets to be served.
 BASE_ASSETS_PATH=/
+
+# This origin trial token is used to enable WebVR in Android Chrome for hubs.mozilla.com.
+# You can find more information about getting your own origin trial token here:
+# https://github.com/GoogleChrome/OriginTrials/blob/gh-pages/developer-guide.md
+ORIGIN_TRIAL_TOKEN="AmTuFlYFGJ4KEbPVE20U0qoWZI3NZuaO8bjjcQvQI4OvDVC4Iyun5gkD8lwtNbrEzh617m5nig0+8QC+Pz6powYAAABVeyJvcmlnaW4iOiJodHRwczovL2h1YnMubW96aWxsYS5jb206NDQzIiwiZmVhdHVyZSI6IldlYlZSMS4xTTYyIiwiZXhwaXJ5IjoxNTM0ODg3ODE1fQ=="
+ORIGIN_TRIAL_EXPIRES="2018-08-21"