[Issue]: remove or qualify reference to in-memory array layout

[d-v-b]

Describe the issue

This reference to memory layout is a bit confusing:

ngff-spec/index.md

Lines 923 to 924 in c69c54c

	These axes relate to the memory or on-disk order insofar as the last dimension is contiguous
	when the zarr array is c-order (the default for zarr version 2, and the only option for zarr version 3).

• For Zarr V2, per the spec order does not default to C. A default order is an implementation decision.
• For Zarr V3, the decoded (in-memory) order is not specified, as it is an implementation detail. The encoded (on-disk) order is determined by the array -> bytes codec in the codecs array; it's true that the bytes codec serializes in C order, but a different array -> bytes codec could use a different order. So the statement that C order is the only option is misleading.

TBH I think this entire section could be removed losslessly, but at a minimum the inaccurate statements should probably be made accurate. Happy to open or review a PR that makes this fix.