Improve ESLint v8 example rule

[guilhermesimoes]

Fixes the current error that appears on the site when you delete the ${i} from the example:

Fixable rules must set the meta.fixable property to "code" or "whitespace". Occurred while linting :18 Rule: "astExplorerRule"

With this change it will be easier to modify the example rule to make fixes and suggestions.

[fkling]

Thank you!

[evenjxr]

when i can use it ?

[guilhermesimoes]

It's already live!