Doc: document openSUSE gotcha #944

Job	Run time
build-minimal-sysroots (x86_64)	1m 8s
build-minimal-sysroots (riscv64)	1m 13s
build-minimal-sysroots (arm64)	1m 13s
build-toolchains (ubuntu-latest, x86_64, gnu)	17m 53s
build-toolchains (ubuntu-latest, riscv64, gnu)	12m 28s
build-toolchains (ubuntu-latest, arm64, gnu)	13m 45s
build-toolchains (ubuntu-20.04, x86_64, gnu)	18m 7s
build-toolchains (ubuntu-20.04, riscv64, gnu)	17m 22s
build-toolchains (ubuntu-20.04, arm64, gnu)	14m 52s
build-toolchains (macos-latest, x86_64, gnu)	25m 13s
build-toolchains (macos-latest, riscv64, gnu)	22m 7s
build-toolchains (macos-latest, arm64, gnu)	22m 30s
build-toolchains (ubuntu-latest, llvm, all)	1h 50m 15s
build-arm64	2m 52s
build-llvm	2m 59s
build	3m 6s
build-llvm-arm64	2m 43s
build-llvm-riscv64	2m 47s
build-riscv	2m 23s
run-riscv	0s
run-riscv64-llvm	0s
run-x86_64	0s
run-x86_64-llvm	0s
	4h 54m 56s

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