Embedding a Topic Title link
If you paste a link into the title box when you create a topic it will embed the link under the topic title. You can then change the title to something more descriptive. 
However, if you flark up embedding a link in your new topic title or realise you forgot to add one, it’s actually possible to edit one in later, rather than scrub and start over. 
You need to edit the OP itself (not just the title), and temporarily cut and paste all of the existing content to somewhere else for safe-keeping. Once blank, you can then paste your link into the title box and you should see it generate a onebox in the body text. This should then embed the link into the topic header.
You can then save that, re-open it, and copy paste the original content back in that you saved to one side. And that should be that.