Fix a broken link in a comment.

Change-Id: I2df10d1aefd0be2c9a740838426bf01c03f85f1e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829358Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Caleb Raitto <caraitto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701665}

net/proxy_resolution/proxy_config.h

@@ -31,7 +31,7 @@ class ProxyInfo;
 // take precedence over the manual ones.
 //
 // For more details see:
-// http://www.chromium.org/developers/design-documents/proxy-settings-fallback
+// http://www.chromium.org/developers/design-documents/network-stack/proxy-settings-fallback
 class NET_EXPORT ProxyConfig {
  public:
   // ProxyRules describes the "manual" proxy settings.