Tutorial: Enhance CTestConfig info in Step 8

Add a copy of the CTestConfig.cmake from Step 9 into the directory for Step 8.

Expand the information about the contents of the CTestConfig file and write a brief explanation of where on CDash to acquire the CTestConfig file for a specific project.

CMake Issue: #22663

Do: stage

assigned to @brad.king

changed milestone to %3.22.0

added area:doc workflow:nightly-testing labels

Do: merge

mentioned in commit 09dd52c9

merged

removed workflow:nightly-testing label

mentioned in issue #22663