Add another TODO to the N5 format description.

Following a comment by @hanslovksy:
  What might also be nice is to add the resolution and offset (or the
  affine) to each of s0, s1 etc, so you can load each mipmap level
  individually with the correct transform.

BDV N5 format.md

@@ -51,3 +51,7 @@ For compatibility with Paintera, when exporting to N5 we put the `"multiScale" :
 `s0`, `s1`, etc. have the mandatory N5 dataset attributes.
 
 For compatibility with Paintera, when exporting to N5 we put the `"downsamplingFactors": [x,y,z]` attribute.
+
+> TODO: Additional metadata (for example scaled resolution and affine transform) could be replicated from the XML.
+The idea would be that an individual stack can be used independent of BDV, without the XML.
+We should agree on standard attributes for this.