Added activation section

doc/user/compliance/license_compliance/index.md

@@ -26,8 +26,9 @@ You can take advantage of License Compliance by either:
   [Auto License Compliance](../../../topics/autodevops/stages.md#auto-license-compliance),
   provided by [Auto DevOps](../../../topics/autodevops/index.md).
 
-The [License Finder](https://github.com/pivotal/LicenseFinder) scan tool runs as part of the CI/CD
-pipeline, and detects the licenses in use. GitLab checks the License Compliance report, compares the
+To detect the licenses in use, License Compliance uses the [License Finder](https://github.com/pivotal/LicenseFinder) scan tool that runs as part of the CI/CD pipeline.
+For the job to activate, License Finder needs to find a compatible package definition in the project directory. For details, see the [Activation on License Finder documentation](https://github.com/pivotal/LicenseFinder#activation).
+GitLab checks the License Compliance report, compares the
 licenses between the source and target branches, and shows the information right on the merge
 request. Denied licenses are indicated by a `x` red icon next to them as well as new licenses that
 need a decision from you. In addition, you can [manually allow or deny](#policies) licenses in your