mention HTTPRoute in "Retries and Timeouts" doc

The Features/Retries and Timeouts documentation currently only
mentions that retries and timeouts can be configured using
ServiceProfiles. This branch updates it to also refer to HTTPRoutes and
link to those docs as well.

linkerd.io/content/2-edge/features/retries-and-timeouts.md

@@ -15,10 +15,12 @@ number of times, it becomes important to limit the total amount of time a client
 waits before giving up entirely. Imagine a number of retries forcing a client
 to wait for 10 seconds.
 
-A [service profile](../service-profiles/) may define certain routes as
-retryable or specify timeouts for routes.  This will cause the Linkerd proxy to
-perform the appropriate retries or timeouts when calling that service.  Retries
-and timeouts are always performed on the *outbound* (client) side.
+Timeouts can be configured using either the [HTTPRoute] or[ServiceProfile]
+resources. Currently, retries can only be configured using [ServiceProfile]s,
+but support for configuring retries using [HTTPRoutes] will be added in a future
+release. Creating these policy resources will cause the Linkerd proxy to perform
+the appropriate retries or timeouts when calling that service. Retries and
+timeouts are always performed on the *outbound* (client) side.
 
 {{< note >}}
 If working with headless services, service profiles cannot be retrieved. Linkerd
@@ -75,3 +77,6 @@ Configuring retries is always a trade-off between improving success rate and
 not adding too much extra load to the system. Retry budgets make that trade-off
 explicit by letting you specify exactly how much extra load your system is
 willing to accept from retries.
+
+[ServiceProfile]: ../service-profiles/
+[HTTPRoute]: ../httproute/