Fix unintended guide chapter scrolling when visit by turbo [skip ci]

[unasuke]

Motivation / Background

step to reproduce

1. Access https://edgeguides.rubyonrails.org
2. Visit "Upgrading Ruby on Rails" or any else page by clicking guides index
3. "Chapters" scrolls end of list

Ruby.on.Rails.Guides.-.Google.Chrome.2024-10-13.04-14-09.mp4

When visiting a guide page by turbo, the navHighlight function fires the scrollIntoView API.
Then, the chapter scrolls to the end of the chapter list by the updateHighlight function because IntersectionObserver's time origin is the first page loaded.

Detail

To fix this, add "is the page navigated by directly" to the condition of the call updateHighlight function.

Additional information

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.