The pages that refer to Touchdisplay 2 probably need rearchitecting

[JamesH65]

I've added some CM specific data in another PR, but the pages could really do with a reshuffle to make them a bit saner. There is duplicate data and its clear the TD2 stuff was added later when it came out.

documentation/asciidoc/accessories/touch-display-2/about.adoc
documentation/asciidoc/accessories/display/display_intro.adoc
documentation/asciidoc/computers/compute-module/cmio-display.adoc

[lurch]

(I preemptively added this to "backlog", as I assume that no-one has time to tackle this any time soon, and we don't want the stalebot to auto-close this issue)

[lurch]

#4002 is also asking for extra clarification that when using a Touchdisplay with the Pi 5, you need to use the specific 15->22 pin DSI cable, you can't use a 15->22pin CSI cable.