Clarify in docs: UXarray supports only spherical 2D grids with convex faces

[Sevans711]

Closes #1597
Closes #1615

Overview

Clarifies in readthedocs pages: UXarray supports only spherical 2D grids with convex faces.

As per discussion in issue 1615:

• (1) Adds the question, "What does UXarray assume about grids?" and its answer to the FAQs page
• (2) Adds the new section, "Additional Assumptions of UXarray" on the grid-formats page

As per discussion in issue 1597:

• Adds .. note:: clarifying these assumptions in the "Why UXarray?" overview page.
• Clarifies "spherical" assumption.

Labeling this PR with "bug" in addition to "documentation", as in 1615, because uxarray currently silently handles non-convex cases incorrectly.

This PR does not update the UXarray README as originally proposed, because these details might be too specific to include in the README itself. But it should still solve the fundamental problem of lack of clarity in the docs regarding these assumptions, so it should be safe to close the underlying issues when this PR merges.

PR Checklist

General

• An issue is linked created and linked
• Add appropriate labels
• Filled out Overview and Expected Usage (if applicable) sections

Documentation

• [N/A] Docstrings have been added to all new functions
• [N/A] Docstrings have updated with any function changes
• [N/A] Internal functions have a preceding underscore (_) and have been added to docs/internal_api/index.rst
• [N/A] User functions have been added to docs/user_api/index.rst

[erogluorhan]

Labeling this PR with "bug" in addition to "documentation", as in 1615, because uxarray currently silently handles non-convex cases incorrectly.

Since the PR does only documentation type of work, removed the bug label to avoid any confusions.

[erogluorhan]

Thanks a lot for this work! Please find a few inline comments below

[Sevans711]

Thank you for your review and suggestions @erogluorhan! I believe I have incorporated them all, though with some rephrasing on my part. If I mangled anything during the rephrasing please let me know. Small notes:

• The .. note:: in the "Why UXarray?" page remains less detailed than the FAQ because many of the details already exist directly above it in the Why UXarray page.
• I didn't add coordinates details in the additions to the grid-formats.rst file in this PR because coordinates details are discussed in the subsequent section in that file already.
• The broken link I added ("Supported Models & Grid Formats") in the FAQ has been fixed, I double-checked that it seems to be working now!

[erogluorhan]

Almost there! Please find a few new comments below

[erogluorhan]

just say "... assumes the grid lies..."

[Sevans711]

Thank you for taking another close look at this, @erogluorhan. I believe 6804e79 addresses most of your comments, aside from the notes below, but please let me know if you have suggestions for more revisions!

Small notes:

• I did add links in the overview.rst file as requested, but I did not add links in the grid-formats.rst file yet (for "UGRID conventions' 2D flexible mesh topology" and "UGRID conventions' 3D layered mesh topology"). I figured it may make sense to avoid putting too many links there in grid-formats.rst. The UGRID conventions doc is already linked above, and more UGRID references are already linked below. But, I don't feel strongly about it; if you prefer links here too just let me know and I would be happy to add them.
• I did not yet remove the "the horizontal portion of the grid…" phrasing; see comment above. I think this point will lead to making some small clarifying changes one way or another, but it may make more sense to hash out those details here before making the changes directly. EDIT: woops, I see your comments now, I guess github was slow to load them or I forgot to refresh the page before I made these changes. Your clarifications sound good. I will push a new commit soon.

[Sevans711]

I believe I've implemented all your suggestions now, and re-requested review. I will take a pause from looking at this for a little while, to avoid duplicating any work / in case my commits have been interrupting your reviews. I appreciate the quick feedback on all of this!

[rljacob]

What is

rx`earch

[Sevans711]

Thank you for taking a look! I believe this was meant to be "research". I also noticed a few other minor typos in the nearby text in this section and fixed those as well.

[rljacob]

Should add that UGRID was officially included in CF.

[Sevans711]

Done!

[erogluorhan]

Looks great; thanks for taking this on and all the review iterations!