Fix validation error type `PR08 ` and check in CI
#### Problem description
In order to have a continuous check by the CI on validation error `PR08` (Parameter description should start with a capital letter), 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 `PR08` type of errors