Fix validation error type `SA04` and check in CI
#### Problem description
In order to have a continuous check by the CI on validation error `SA04` (Missing description for See Also reference), fixing them in the code base enables the addition to the CI for automated testing in the future.

Please see [overview of the errors](https://gist.github.com/198cfa552c727d71bd7360fda66fdbb4).

Todo:

* [ ]     get rid of the errors in the code base
* [ ]     update the `code_check.sh` script to take into account the `SA04` type of errors