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docs(design): what landed in each repository, and where each claim wa… #1899

Job	Run time
examples: the curriculum builds	8m 55s
toolchain: gcc (cold self-host)	9m 38s
build + unit tests (linux x86_64, self-host)	16m 35s
integration: mcpp builds & runs xlings	6m 50s
toolchain: musl + llvm	10m 27s
	52m 25s