docs: add topology2 README with structure and conventions #22667

Job	Run time
LP64-WIP	4m 10s
build-windows (-d, lnl)	9m 40s
manifest-check	3m 19s
build-windows (mtl)	10m 18s
build-windows (lnl)	11m 1s
build-windows (tgl)	10m 54s
build-windows (ptl)	11m 51s
build-linux (mnfst, imx8m imx8ulp)	4m 33s
build-linux (zmain, imx8 imx8x)	4m 53s
build-linux (zmain, imx8m imx8ulp)	3m 41s
build-linux (mnfst, lnl)	5m 59s
build-windows (imx8 imx8x)	11m 3s
build-linux (mnfst, imx8 imx8x)	5m 3s
build-windows (imx8m imx8ulp)	9m 30s
build-linux (zmain, mtl)	4m 34s
build-linux (mnfst, tgl-h)	4m 28s
build-windows (tgl-h)	9m 31s
build-linux (mnfst, tgl)	4m 33s
build-linux (zmain, ptl)	5m 50s
build-linux (mnfst, mtl)	4m 40s
build-linux (mnfst, wcl imx95)	7m 20s
build-linux (zmain, lnl)	4m 33s
build-linux (-d, mnfst, lnl)	5m 21s
build-linux (mnfst, ptl)	5m 20s
build-linux (zmain, tgl-h)	4m 31s
build-linux (zmain, tgl)	4m 3s
compare-linux-win	27s
	2h 51m 6s

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