Improve search provider configuration

[marc1404]

Context

At the time of writing, the website uses minisearch as the search provider with basic configuration. This is built into VitePress by default: https://vitepress.dev/reference/default-theme-search.
It also supports Algolia. Nevertheless, it would also be possible to extend it and use alternative solutions such as Meilisearch.

Prerequisite

It should be determined and settled which search provider will be used for the documentation.

Task

We should review the search provider's configuration options and optimize them for our content.
Possible avenues:

• Weighting between different fields: filenames, frontmatter fields, markdown content, etc.
• What's in scope/indexed by the search?
• Do we need additional tagging/keywords?

How to measure?

• Explorative tests using self-defined search queries to see the search result order.
• As part of Define test set of queries to verify search accuracy #813, a predefined set of queries and expected/preferred results is defined, which could be used for testing.