Review the user docs against what shipped before the parity gate closes

[mmcky]

Part of #147 (close-out: the final task before the PLAN.md close-out).

Why

Gate items update their own documentation lines as they land, and their acceptance criteria say which lines. Nothing checks the docs as a whole against the release that closes the gate. The review of #147 also found documentation lines that describe behaviour the theme does not have and that no gate issue owns. Those lines are collected here. #210, closed on 2026-09-11, recorded where every other part went.

Scope

Review README.md, every page under docs/, and CONTRIBUTING.md against the theme as released at the end of the gate. Start with these lines (the permalinks show them at v2.7.0):

Line	Says	What the theme does	Study row
docs/layout.md L7-L10	"A fixed 50px toolbar: the QuantEcon logo and site title, …"	The toolbar has no site title, and the Home, font-size and GitHub controls go unmentioned	F019
docs/layout.md L52-L53	Below lg (1024px) the outline column is hidden	The outline appears from 1280px	F001
docs/dark-mode.md L4-L6	"the Sphinx sites' dark ground (#222) and white text"	This describes book-theme releases before 0.18.0; 13 lecture repositories pin 0.22.0, which has a navy-charcoal palette. The palette choice is a design question on #187	F029
docs/configuration.md L51	site.title is "the site name in the header and og:site_name"	The header shows the project title; site.title feeds og:site_name and the page-title suffix	F006
docs/notebooks.md L7	"Long outputs are clipped with a scroll region."	Nothing limits output height until QuantEcon/mystmd#106 ships	F069
docs/authors.md	(not mentioned)	The translator credit joins names in English (", " and " and ") on every edition	—

Also:

• Gate items' own lines: confirm that each closed gate item updated the documentation lines its acceptance criteria name (Decide how the CC BY-SA licence footer survives the cutover: a theme default or a per-repo footer.md #203, Launch control cannot be turned off and links to a nonexistent notebooks repo on sites without one #205, Pages emit no rel=canonical, and the favicon link 404s on sites served under a sub-path #207, The "On this page" outline leaves out h4 subsections that the Sphinx panel lists and expands #208), along with any of A reader's light or dark choice is overwritten when the operating system switches appearance #211–Readers cannot copy a section link from the "On this page" outline, which Sphinx lecture sites allow #215 that have landed.
• docs/index.md: point its promise that "where a Sphinx option has no counterpart, its page says so" at the table on the migration checklist page (Lecture repos moving off the Sphinx theme have no checklist of what myst.yml and CI must now set #209). Drop the sentence saying the parity work is tracked in PLAN.md, which the PLAN.md close-out issue coordinates.
• README version URLs: the pinned vX.Y.Z URLs should name the release that closes the gate.

Acceptance criteria

• Every line in the table describes the shipped behaviour, or names the open issue that will change it.
• Every documentation line named in a closed gate item's acceptance criteria is confirmed updated.
• docs/index.md points its no-counterpart promise at the migration checklist table, and no docs page presents PLAN.md as the live record of the parity work.
• README's pinned vX.Y.Z URLs name the release that closes the gate.
• The PR changes documentation only.

Context

• Replaces: the user-docs half of PLAN.md and the user docs claim book-theme parity and behaviour that the code does not deliver #210.
• Order: it runs after every other open gate item, and before the PLAN.md close-out.

[mmcky]

All criteria are now met, so closing.

The substance was delivered by #229: six documentation pages corrected against what the theme actually does — the toolbar contents (no site title; Home, font-size and GitHub were unmentioned), the width at which the outline appears (1280px, not 1024px), the dark ground provenance, what site.title feeds (og:site_name and the title suffix, not the header), notebook output height, and the translator names being joined in English on every edition. Copilot caught one incorrect correction in that PR — the overflow-menu sentence — which was fixed in 788d44ffd.

The last outstanding criterion was the README pinned vX.Y.Z URLs, which could only name the release that closes the gate. That release is now cut: v3.0.0 is published with quantecon-theme.zip attached, and #236 bumped both URLs — the site.template example and the git-metadata plugin — to v3.0.0.

The doc-line criterion was also confirmed against main rather than assumed: six of the seven closed gate items were documented by their own PR, and #206 was a genuine gap (#225 shipped output-image centring with no documentation), which docs/notebooks.md in #229 closes.