* Adding an exception section covering key derivation use cases.
* Updating recommended salt length to 256 bits as recommended by NIST
* Improve title to make it explicit we don't target KDF
* Altered some small points
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Co-authored-by: Egon Okerman <egon.okerman@sonarsource.com>
Inline adoc files when they are included exactly once.
Also fix language tags because this inlining gives us better information
on what language the code is written in.
