gh-157525: Docs: align documentation homepage layout and chapter order

[m-aciek]

Closes #157525.

Replace the documentation homepage’s two independent columns with a single list that flows across rows on wider screens and stacks vertically on smaller screens. Related sections appear next to each other on desktop and consecutively on mobile.

Reorder the root table of contents to match the homepage, so chapter navigation follows the same sequence.

Suggestions on the section order are welcome. The aim is to keep related topics together while maintaining a consistent reading order across layouts and chapter navigation.

Desktop: before and after

Before:

After:

Mobile: before and after

Before	After

• Issue: Docs: align homepage reading order with chapter navigation #157525

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #34558090 | 📁 Comparing 40eaa33 against main (e5fbabb)

  🔍 Preview build  

1 file changed

± index.html

[hugovk]

Looking at the desktop before and after, I think I prefer the before:

I usually read down the columns, as they're closer to each other, and not row-by-row, so find it more useful to have the 3 x reference next to each other in a column.

[nedbat]

TBH, I prefer the new row-by-row, but only slightly. Any order in a 2-by-X table is going to be an odd way to present what is conceptually a single list, but row-by-row means the two items at the top of the page are the first two items.

[m-aciek]

I investigated a conservative approach — keeping the current display order and adjusting contents.rst accordingly — but that would interweave the different chapter types in contents.rst.

[m-aciek]

Let me create an alternative draft PR with flow by columns for preview.