[core] Batch small changes

[oliviertassinari]

• [docs] Use Oxford comma convention ed2454c
• [docs] Fix v5 migration css prop fe56dc1
• [docs] The bundle size resonates more for unstyled 0288b8e
• [docs] Fix broken ToggleButtons demo 2547aed: Fix display of https://next.material-ui.com/components/toggle-button/#exclusive-selection.
• [docs] Remove unused code 417e3a3: A follow-up on [docs] Use public next/router events API #26233. cc @eps1lon for review
• [core] Remove issue template that is almost never used: f347ed5. From what I understand, the last time the issue template was used is [theme] Improve the breakpoints values #21902. 10 months ago. It seems safe to remove it.

[mui-pr-bot]

No bundle size changes (experimental)

Generated by 🚫 dangerJS against 1e93da2

[eps1lon]

We haven't heard back from google. Don't just remove things you don't have any information about.

[oliviertassinari]

We haven't heard back from google.

@eps1lon It's precisely the information given in the inaction that triggers my intention of removing the snippet. I have interpreted this very long delay (we talked about it more than a year ago?) as a demonstration of how much importance Google gives to the project and how the likeliness of the integration is to happen: too low.

I have reverted. How about we send MD a follow-up? And remove the issue template if we don't hear back from them one month after?