Minor changes to ZEP0000 and add a new page for ZIC

[MSanKeys963]

Hi all. This PR contains the following:

• Consolidate the discussion avenues for ZEPs in ZEP0000

Previously, there were several avenues to discuss ZEPs like Gitter and GitHub discussions and issues which might confuse the author and the community. This may also lead to fragmented discussions, while the idea of ZEP is to have all of the discussions in a single place. After this PR, all of the discussions related to current ZEPs will take place via creating issues in zeps repo or zarr-specs repo.

• Add a page for ZIC (can be viewed at https://zarr.dev/zeps/zic/ after merging this PR)

Borrowed from: https://github.com/zarr-developers/governance/blob/main/GOVERNANCE.md#zarr-implementation-council-zic

• and minor formatting changes in ZEP0000

CC: @zarr-developers/steering-council @zarr-developers/implementation-council

[MSanKeys963]

Please let me know if there are any objections to this. You can vote with 👍🏻 and 👎🏻.

CC: @joshmoore @rabernat @jbms @jstriebel @WardF (from today's ZEP meeting)

[joshmoore]

Few quick comments. Thanks for this, @MSanKeys963.

[MSanKeys963]

Thanks, @joshmoore and everyone for 👍🏻 and review. I've made the final changes and I think we're ready to merge this.
Let me know what you think.

[MSanKeys963]

Please raise your concerns if there are any. I want to get this in ASAP!
I'll wait until 24 hours before I merge it. Thanks!

[MSanKeys963]

Alright, going ahead with this now.
We can revert if there are any significant concerns. Thanks!