Update README.md

Co-authored-by: Alan Shaw <[email protected]>

Author: fforbeck

README.md

@@ -20,7 +20,7 @@ You can start editing the page by modifying `app/page.tsx`. The page auto-update
 
 ### Using an alternate w3up service
 
-By default, this app connects to https://up.web3.storage, and uses web:web3.storage as provider. To use an alternate service, specify the service URL and DID in your environment variables, like:
+By default, this app connects to `https://up.web3.storage`, and uses `did:web:web3.storage` as provider. To use an alternate service and/or provider, specify the service URL, service DID and provider DID in your environment variables, like so:
 
 ```
 NEXT_PUBLIC_W3UP_SERVICE_URL=https://your.w3up.service