Hawk review concepts

* [x] Clarify usage of token versus of identifier
* [x] Review and improved doc
* [x] Reformat of current credentials in hello (?..maybe wrong to mention credentials)
* [ ] Complete glossary

For this pull request, its author has lost 12 points of energy.
`Identifier` is confusing I think because `Identifier` means `id`, here we are talking about `Token` from its `id` to be more specific.