[v4-docs] wrong content in docsearch meta

[siriwatknp]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Current behavior 😯

docsearch team mentioned in this PR that some of the links in v4 has wrong content.

Only the urls for data-grid has wrong content.

<meta name="docsearch:version" content="master">

Expected behavior 🤔

It should be

<meta name="docsearch:version" content="v4">

Steps to reproduce 🕹

Steps:

1. checkout https://v4.mui.com/components/data-grid/
2. in element devtool, search for docsearch

Context 🔦

No response

Your environment 🌎

`npx @mui/envinfo`

  Don't forget to mention which browser you used.
  Output from `npx @mui/envinfo` goes here.

Order ID 💳 (optional)

No response

[oliviertassinari]

@siriwatknp I work on this in #2657. I think that the next step for this issue is to update https://github.com/mui-org/material-ui/blob/v4.x/docs/public/_redirects#L151-L159 to point to the docs-v4 branch.

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Also note that I fixed a different issue with Algolia on #2655 (it's similar to this one, but for v5, this time, not v4).

[cherniavskii]

It's set to "v4" now: