add a bit about making discovery consistent

keps/sig-api-machinery/3903-unknown-version-interoperability-proxy/README.md

@@ -192,9 +192,23 @@ incorrectly or objects being garbage collected mistakenly.
 
 We will use the existing `StorageVersion` API to figure out which resources an apiserver can serve.
 
+We will also need to make discover reports the same set of resources everywhere. We propose
+routing discovery requests from old-apiservers to the new api-server, so that all discovery
+requests reflect the newest one. We specifically rule out merging discovery docs, because
+merging discovery is:
+
+* complicated 
+* represents an intermediate state which may not even make sense
+
+By routing all discovery requests to the newest apiserver, we can ensure that namespace and gc
+controllers do the right thing, which is what they would be doing if the upgrade happened
+instantaneously. 
+
+
 API changes:
 * To the apiservices API, add an "serviceableBy" clause, a list of
   apiservers which believe they can serve the group-version.
+* To the ??? API, we will add the public key for communication with an apiserver.
 
 API server change:
 * A controller adds the apiserver to the list of `serviceableBy`s for its built-in
@@ -203,7 +217,11 @@ API server change:
   apiserver identity work.)
 * A new handler is added to the stack:
   - If the request is for a group/version the apiserver doesn't have locally, it
-    will proxy the request to ag `serviceableBy`s if one is available, if one is not available, then we will return a 503 (there is a small possibility of a race between the controller registering the apiserver with the resources it can serve and receiving a request for a resource that is not yet available on that apiserver).
+    will proxy the request to ag `serviceableBy`s if one is available, if one is not 
+    available,then we will return a 503 (there is a possibility of a race 
+    between the controller registering the apiserver with the resources it can 
+    serve and receiving a request for a resource that is not yet available on 
+    that apiserver).
 
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