Link to similarity plugin still reference 2.x branch

[grib0]

This page about similarity has a link to the 2.x branch. When clicking, you are going to the 2.x page, with an info section inviting you to go to latest version, but then you are redirect to the root reference version loosing your navigation.

https://www.elastic.co/guide/en/elasticsearch/reference/current/similarity.html

Section : Pluggable Similarity Algorithms

The link should point to
https://www.elastic.co/guide/en/elasticsearch/reference/7.7/index-modules-similarity.html instead of
https://www.elastic.co/guide/en/elasticsearch/guide/2.x/pluggable-similarites.html

[nik9000]

That is actually referencing "The Definitive Guide" which we never updated beyond 2.x. We really should link it to something in the current branch. @jrodewig, do you have any ideas here?

Also, I'm going to move this bug into the "elasticsearch" repo because that is where we have to fix it.

[elasticmachine]

Pinging @elastic/es-search (:Search/Search)

[elasticmachine]

Pinging @elastic/es-docs (>docs)

[jrodewig]

Thanks for raising @nik9000. I don't think we have a good substitute for these pages in the ES reference guide.

However, I think we can either remove the links or replace them with links to the algorithms in wikipedia:

• https://en.wikipedia.org/wiki/Okapi_BM25
• https://en.wikipedia.org/wiki/Tf%E2%80%93idf

I can work on a PR.

[jrodewig]

Closed by #56925.