Merge pull request #4068 from segmentio/jfoskin-patch-1

Added Proxy Server Side Note

Author: forstisabella

src/connections/sources/catalog/libraries/website/javascript/custom-proxy.md

@@ -22,6 +22,9 @@ You need to set up two important parts, regardless of the CDN provider you use:
 - Proxy to Segment CDN (`cdn.segment.com`)
 - Proxy to Segment tracking API (`api.segment.io`)
 
+> info " "
+> Segment only has the ability to enable the proxy setting for the Web (Analytics.js) source. Details for mobile source proxies are in the [Analytics for iOS](/docs/connections/sources/catalog/libraries/mobile/ios/#proxy-https-calls) and [Analytics for Android](/docs/connections/sources/catalog/libraries/mobile/android/#proxying-http-calls) documentation.  It is not currently possible to set up a proxy for server sources using the Segment UI.
+
 ## Set up
 
 Follow the directions listed for CloudFront or use your own CDN setup. Once you complete those steps and verify that your proxy works for both `cdn.segment.com` and `api.segment.io`, [contact Segment Product Support](https://segment.com/help/contact/) with the following template email: