Algolia placeholder does not work docusaurus.config.js file.

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Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

According to https://docusaurus.io/docs/search#customizing-the-algolia-search-behavior

We can use

placeholder
type: string | default: "Search docs" | optional

The placeholder of the input of the DocSearch pop-up modal.

... this does not work and we get a TS error

theme-search-algolia.d.ts(12, 5): The expected type comes from property 'algolia' which is declared here on type 'ThemeConfig'

Reproducible demo

No response

Steps to reproduce

Add placeholder to Algolia field in Docusaurus config

Expected behavior

Search box modal would use my value instead of the default "Search docs"

Actual behavior

TS error

theme-search-algolia.d.ts(12, 5): The expected type comes from property 'algolia' which is declared here on type 'ThemeConfig'

Your environment

• Public source code:
• Public site URL:
• Docusaurus version used:
• Environment name and version (e.g. Chrome 89, Node.js 16.4):
• Operating system and version (e.g. Ubuntu 20.04.2 LTS):

Self-service

• I'd be willing to fix this bug myself.