Fix #2280 - code block highlights

[BuckeyeCoder]

Code reviewed the entire site's code blocks for those that use a highlight. Found 3 that needed adjusting.

Only other change was from the Markdown linter which prefers underscores for italic text instead of asterisks for some reason. Either are allowed and assuming we all use the same linter I allowed the linter's opinionated change.

Did not see an AUTHORS.md to add to; if you need that to maintain MIT let me know and we'll add it.

[leaanthony]

Thanks for taking the time to do this!

[leaanthony]

Did not see an AUTHORS.md to add to; if you need that to maintain MIT let me know and we'll add it.

We keep a list of contributors in the main project documentation, which is rendered here: https://wails.io/credits/#contributors

The source of this is: https://github.com/wailsapp/wails/blob/master/.all-contributorsrc

I think we could make this more obvious in the guide and keep it updated via actions.

We also encourage everyone to update CHANGELOG.md. I go through each commit and update it prior to releases but it's better if it's done as the PRs are done.