check mincopies is satisfied even when numcopies is known to be satisfied

I had been assuming that numcopies would be a larger or at most equal to
mincopies, so no need to check both. But users get confused and use configs
that don't really make sense, so make sure to handle mincopies being larger
than numcopies.

Also add something to the mincopies man page to discourage this
misconfiguration.

This commit was sponsored by Denis Dzyubenko on Patreon.

Types/NumCopies.hs

@@ -145,9 +145,9 @@ isSafeDrop :: NumCopies -> MinCopies -> [VerifiedCopy] -> Maybe ContentRemovalLo
  - dropped from the local repo. That lock will prevent other git repos
  - that are concurrently dropping from using the local copy as a VerifiedCopy.
  - So, no additional locking is needed; all we need is verifications
- - of any kind of N other copies of the content. -}
-isSafeDrop (NumCopies n) _ l (Just (ContentRemovalLock _)) = 
-	length (deDupVerifiedCopies l) >= n
+ - of any kind of enough other copies of the content. -}
+isSafeDrop (NumCopies n) (MinCopies m) l (Just (ContentRemovalLock _)) = 
+	length (deDupVerifiedCopies l) >= max n m
 {- Dropping from a remote repo.
  -
  - To guarantee MinCopies is never violated, at least that many LockedCopy