conditional: Document the new expression filter and new Pi5 boot variables

[timg236]

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[timg236]

@lurch - Any more comments?

[lurch]

This is not the PR to tweak Raspberry Pi "family" terminology so resolving this comment

Haha, fair enough.

since the naming is consistent within the page.

Sorry to keep nit-picking, but if you wanted to be consistent with the terminology on the rest of https://www.raspberrypi.com/documentation/computers/config_txt.html you'd need to use "Flagship models since Raspberry Pi 5, Compute Modules since CM5, and Keyboard models since Pi 500".
However that's a bit of a mouthful though, which is why I'd be happy to approve this PR if you changed "Raspberry Pi 5 and newer flagship devices only." to "Raspberry Pi 5 and newer devices only." or "Raspberry Pi 5 only." (because otherwise people might think that this only applies to Pi5 and not CM5).

[timg236]

I'm ignoring the "Pi 5 family" vs "Flagship" vs "Pi 5" changes because the documentation repo is already inconsistent and I'm not sorting out as part of this change.

[helenlynn]

We (and third parties) often use "flagship" to mean the credit-card-sized Raspberry Pis specifically, so we shouldn't say "flagship devices only" unless we positively want to indicate that something does not apply to CMs or Raspberry Pi x00 devices. "flagship devices only" for something that also applies to CM5 and Pi 500 is inaccurate.

[timg236]

I think you may need to update other references to flagship.
Personally I would recommend not using flagship anywhere in technical documentation because it doesn’t mean much to a typical user.

[helenlynn]

Agreed; it's rarely if ever going to be clear without additional explanation. But for now I will settle for this particular PR not adding confusion :)