[software] Add README #1957

Job	Run time
tc-gcc	24s
riscv-isa-sim	14s
check-opcodes	5s
tc-llvm	48s
verilator	13s
verilator-model (minpool)	6m 30s
verilator-model (mempool)	12m 4s
build-apps-gcc (minpool)	50s
build-apps-gcc (mempool)	34s
check-bootrom	9s
build-apps-llvm (minpool)	49s
tc-halide	9s
build-apps-llvm (mempool)	48s
build-apps-halide (minpool)	36s
build-apps-halide (mempool)	1m 40s
run-apps-halide (minpool)	41s
unit-test	2m 22s
run-apps-halide (mempool)	2m 50s
run-apps-gcc	0s
run-apps-llvm	0s
clean-up	5s
clean-up-compile-runs (minpool)	2s
clean-up-compile-runs (mempool)	4s
	31m 57s

Provide feedback