[docs] Menu unstyled page auto focus to useMenu and useMenuItem hooks demo

[ivan-ngchakming]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Current behavior 😯

Upon opening the Menu unstyled componet doc, the useMenu and useMenuItem hooks demo is set as the active element automatically, force scrolling down to this demo instead of the start of the page.

Expected behavior 🤔

Disable set focus to elements in this demo. So user can view this page from the top upon visiting the page.

Steps to reproduce 🕹

Steps:

1. visit https://mui.com/base/react-menu/

Context 🔦

Encountered this while working on #31012, didn't realize there were two more demo above until fiddling around with the page for a while. Would love to work on a PR if needed.

Your environment 🌎

`npx @mui/envinfo`

  I am using Firefox and Chrome btw.

[adhyayaThakur]

Hello, may I take this issue.

[michaldudak]

@adhyayaThakur sure, go ahead. Let's modify the demo to not display the menu immediately, but after clicking on a button (similar to other demos).