Within-section navigation missing for smaller screens, global contents difficult to navigate.

Documentation

Problem

Within a documentation section (I'm using that term to refer to sub-documents like, say, the tutorial, not sure if there is an official term), there is currently no way to go "up" a level to see the contents of that section when not using a full width screen:

Full width screens have breadcrumbs at the top

The "table of contents" link takes you back to the global contents, which are not usable, as they contain every header from every document in the docs - take a scroll if you haven't in awhile: https://docs.python.org/3/contents.html

It's also not obvious which document you are in, as "table of contents" is ambiguous - the only place that "tutorial" is present is in the URL.

This makes it quite challenging to navigate the docs on mobile, or when splitting a screen and reading in a narrow window.

Desired solution

I would like...

• the sidebar "Table of Contents" to be replaced with the title of current document section when one is within a document section (eg. /{version}/tutorial/interpreter.html), and with a link to the global ToC when one is in a section ToC (eg. /{version}/tutorial/).
• The maxdepth of the global ToC to be reduced to 2 to make it usable

I will follow on with a PR momentarily...

Linked PRs

• gh-123453

首先检查文档侧边栏导航、全局目录以及 /{version}/tutorial/interpreter.html 和 /{version}/tutorial/ 等章节 URL。完成的标准是：窄屏能够识别当前章节，提供返回该章节内容的导航，将章节 ToCs 链接到全局 ToC，并将全局 ToC 的 maxdepth 限制为 2。issue 中已经引用了一个已链接的 pull request。