[DOCS] Update doc_values documentation

[antoinewg]

According to https://kb.objectrocket.com/elasticsearch/when-to-use-the-keyword-type-vs-text-datatype-in-elasticsearch, the string type (with option analyzed) has been replaced by text after 6.0 (This version is 7.4)

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[ghost]

Hi @TonioGarcia07, we have found your signature in our records, but it seems like you have signed with a different e-mail than the one used in your Git commit. Can you please add both of these e-mails into your Github profile (they can be hidden), so we can match your e-mails to your Github profile?

[elasticmachine]

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

[elasticmachine]

Pinging @elastic/es-docs (>docs)

[cbuescher]

Hi @TonioGarcia07, generally looks good to me, can you also add the recently introduced annotated_text field to the list which, looking at the code, also doesn't support doc_values?

[cbuescher]

@TonioGarcia07 thanks for the update, will run our docs CI tests before merging.

[cbuescher]

@elasticmachine test this please