add config option for k-choices rebalance interval

src/Hash2Pub/FediChordTypes.hs

@@ -459,6 +459,8 @@ data FediChordConf = FediChordConf
     -- ^ fraction of capacity below which a node considers itself underloaded
     , confKChoicesMaxVS             :: Word8
     -- ^ upper limit of vserver index κ
+    , confKChoicesRebalanceInterval :: Int
+    -- ^ interval between vserver rebalance attempts
     }
     deriving (Show, Eq)