lib/model: Typo in folder_recvonly.go (#7919)

lib/model/folder_recvonly.go

@@ -26,7 +26,7 @@ func init() {
 /*
 receiveOnlyFolder is a folder that does not propagate local changes outward.
 It does this by the following general mechanism (not all of which is
-implemted in this file):
+implemented in this file):
 
 - Local changes are scanned and versioned as usual, but get the
   FlagLocalReceiveOnly bit set.