update known issues

Signed-off-by: Jakub Sokołowski <jakub@status.im>

README.md

@@ -70,3 +70,5 @@ docker build -t statusteam/auto-sticker-pinner:latest .
 
 * Currently IPFS Cluster API does not expose any info about possible pinning errors
   - We run `GET /pin/{chash}` to check if it was pinned as an alternative
+* Checking pin status for a cluster returns multiple statuses
+  - We check if all of them are of certain type, and ignore other mixed states

ipfs.py

@@ -22,6 +22,7 @@ class IpfsPinner:
             peer in self.ls(chash)['peer_map'].values()
         ]
 
+    # See: https://cluster.ipfs.io/documentation/guides/pinning/
     def status(self, chash):
         statuses = self.statuses(chash)
         if all(s == 'pinned' for s in statuses):