Add additional documentation on maximum number of resources (#33)

Fixes #27.

I was looking into what value to set this too when,
I encountered #27 and decided to just fix it in place.

Fix link, add quotes

src/Data/Pool/Internal.hs

@@ -77,8 +77,13 @@ defaultPoolConfig
   -- /Note:/ the elapsed time before destroying a resource may be a little
   -- longer than requested, as the collector thread wakes at 1-second intervals.
   -> Int
-  -- ^ The maximum number of resources to keep open __across all stripes__. The
-  -- smallest acceptable value is @1@.
+  -- ^ The maximum number of resources to keep open __across all stripes__.
+  -- The smallest acceptable value is @1@ per stripe.
+  -- If you don't use 'setNumStripes' then set this to the amount of
+  -- capabilities (using 'GHC.Conc.numCapabilities').
+  -- If you don't do this your program might crash with "poolMaxResources
+  -- must not be smaller than numStripes",
+  -- especially if you move your program to a machine with bigger thread count.
   --
   -- /Note:/ for each stripe the number of resources is divided by the number of
   -- stripes and rounded up, hence the pool might end up creating up to @N - 1@