Tweak implicit classes overview

[som-snytt]

Per scala/scala3#3654

[SethTisue]

I've never seen the backquote trick in a real codebase. Do people really do that?

I think it might be better to relegate it to a footnote than to actually suggest it in the main text?

[som-snytt]

I guess by real codebase you mean Akka. I've seen it recommended in public chat, and I was like, hey I thought that was my idea.

I'm not invested in overview examples for obsolete features, so I pushed the minimum viable correction.

There should be a big label somewhere that says, "Overviews are not the spec."

Scala 3 is still loose about where the holiest words are kept.

[som-snytt]

I forgot the preserve the corrected sip URL, but it forwards anyway.