Clarify the minimum ChromeOS version required

[kccuber-scratch]

Resolves #465

Changes the text on the unsupported-browser page to clearly show the minimum ChromeOS version required.

[WorldLanguages]

@kccuber-scratch This was phrased this way because many Chromebook users know that Chrome OS auto-updates, and they believe they are on the latest version, even when they are not. I'm not sure if Chrome OS does a good job of telling users that they are stuck in a very old version of Chrome.

I'm not really sure if this change "clarifies" anything. If someone is viewing this page, there's a 99% chance they are on it because they are running an unsupported browser version. The "old Chromebook" wording could help the user understand that, unlike other operating systems, they cannot update to Chrome 96 by rebooting Chrome.

The current wording should not be understood as a statement such as "7 year old Chromebooks cannot run Scratch Addons". The goal instead is to let the user understand that they are probably running an outdated OS, not an outdated browser.

[kccuber-scratch]

honestly if you have a trashy school provided chromebook that cant even run chrome 96 its a miracle you manage to even use it without wanting to break your device into pieces

I think a better solution would be to go back to the "chromebooks less than x years old" but add a tooltip when hovered over or clicked on to clarify that the user should find a way of obtaining a new device soon