fix: #67

[lpofredc]

• fix: position areas API return 404 errors when no content. status code is now 204 (no-content). Require a data check on axios promise in frontend:

  this.$axios
      .$get(
        myUrl
      )
      .then((data) => {
        if (data && myOtherCondition) {
           doSomething
        }
      )
      .catch...

• docs: List actual atlas species and groupings

• wip: work on auto update taxa match between VisioNature and TaxRef