Update cmake package example in Porter's Handbook

[carlavilla]

Summary

Update cmake package example in Porter's Handbook

PR: 242566

Test Plan

Compile the Porter's Handbook

[mat]

What I read from the PR is that the example port should be removed instead of being changed.

[carlavilla]

In D23410#513498, @mat wrote:

What I read from the PR is that the example port should be removed instead of being changed.

Yes, that's the first comment of Tobias, but in his last comment he says

"If you prefer to keep an example, I would suggest `devel/kf5-kcrash'.
It has a very small plist at the moment (13 lines), and uses the sub."

IMHO I think that's better to have an example instead of removing it.

[bcr]

Also good from my side.