strike completed robustness items from todo

README.md

@@ -13,10 +13,7 @@ The idea is that we can have much larger limits if we scale down the volume of t
 - keep track of currently subscribed PDSes in application state
 - discover PDSes via crawling instead of hardcoding 1 (lol)
     - do not allow PDSes with more than 1000 repos
-- robustness:
-    - try to reconnect (tamed exponential backoff) if we lose connection to a PDS
-    - allow catchup with cursor based on history data
 - history:
-    - timestamp instead of seq number as key
+    - timestamp instead of seq number as key ?
     - purge based on ttl
     - takedowns probably