chore(version): update cs3d version and add iframe documentation (#3474)

platform/docs/versioned_docs/version-2.0-deprecated/viewer/environment-variables.md

@@ -0,0 +1,27 @@
+---
+sidebar_position: 3
+sidebar_label: Environment Variables
+---
+# Environment Variables
+
+There are a number of environment variables we use at build time to influence the output application's behavior.
+
+```bash
+# Application
+NODE_ENV=< production | development >
+DEBUG=< true | false >
+APP_CONFIG=< relative path to application configuration file >
+PUBLIC_URL=<>
+VERSION_NUMBER=<Set by CircleCI>
+BUILD_NUM=<Set by CircleCI>
+# i18n
+USE_LOCIZE=<false>
+LOCIZE_PROJECTID=<ProjectID to pull translations for>
+LOCIZE_API_KEY=<To enable Locize live editing of translations>
+```
+
+## Setting Environment Variables
+
+- `npx cross-env`
+- `.env` files
+- env variables on build machine, or for terminal session