fix(content): remove sharded IPLD array file

[yiannisbot]

The Sharded IPLD Arrays are not used in Filecoin anymore, hence, this PR removes the subsection from the Appendix.

[mikeal]

@rvagg should we pull any of this into the IPLD docs or specs site? We still have implementations of this, they just aren’t used in Filecoin anymore.

[yiannisbot]

If you think it's useful to keep in this spec, I suggest that we move it in the libraries section together with the rest of the IPLD stuff.

[rvagg]

Our vector spec covers this well enough, I think it's already 1:1 (although slightly more configurable?) with sharray so I don't think we need to capture anything here. This will be a good one to get to with ipld-prime now that they're poking at ADLs but we have it covered with the spec and the sharray code.

[yiannisbot]

It sounds to me that this section is not needed in this spec. So, I suggest that: i) approve this PR and remove the section, ii) include any extra links and pointers, if needed, in the Libraries section with a PR there.