EUDC instructions (#224)

* Docs updates for refreshJwtToken

* Removed a semicolon

* EUDC language

Author: Brad Umbaugh

README.md

@@ -38,6 +38,12 @@ or with a CDN:
 <script src="https://unpkg.com/@iterable/web-sdk/index.js"></script>
 ```
 
+# Iterable's European data center (EUDC)
+
+If your Iterable project is hosted on Iterable's [European data center (EUDC)](https://support.iterable.com/hc/articles/17572750887444), you'll need to configure Iterable's Web SDK to interact with Iterable's EU-based API endpoints. 
+
+To do this, on the web server that hosts your site, set the `IS_EU_ITERABLE_SERVICE` environment variable to `true`. 
+
 # API
 
 Below are the methods this SDK exposes. See [Iterable's API Docs](https://api.iterable.com/api/docs) for information on what data to pass and what payload to receive from the HTTP requests.
@@ -460,6 +466,7 @@ import { updateUserEmail } from '@iterable/web-sdk';
 updateUserEmail('[email protected]').then().catch();
 ```
 
+
 # FAQ
 
 ## How do I make API requests with the SDK?