:bug: Clarify licensing checks documentation

[mxmehl]

What kind of change does this PR introduce?

This PR fixes a typo for the LICENSES directory, which was in one place called LICENSE directory.

Furthermore, it makes a proposal for a better wording of where licenses are searched for. As I am not aware how the tool works internally, this should be reviewed.

• [x] PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

The check documentation and the recommendations are unclear and partly misleading.

Does this PR introduce a user-facing change?

NONE