add some documentation for scheduling and s3 client #4488

Job	Run time
windows-shared-libs	19m 23s
byo-crypto	3m 19s
clang-sanitizers (,address,undefined)	19m 34s
windows	19m 40s
windows-vc17 (x86)	19m 48s
windows-vc17 (x64)	19m 51s
macos	16m 47s
linux-shared-libs	19m 40s
linux-compat (manylinux2014-x64)	18m 56s
linux-compat (manylinux2014-x86)	19m 54s
linux-compat (manylinux1-x64)	19m 7s
windows-app-verifier	42m 59s
macos-x64	17m 15s
linux-debug	19m 16s
downstream	19m 12s
linux-compat (manylinux1-x86)	19m 52s
linux-compat (al2-x64)	19m 43s
clang-sanitizers (,thread)	21m 28s
linux-compiler-compat (clang-15)	20m 53s
linux-compiler-compat (clang-8)	20m 33s
linux-compiler-compat (clang-11)	20m 5s
linux-compiler-compat (clang-9)	20m 14s
linux-compiler-compat (clang-6)	20m 15s
linux-compiler-compat (gcc-8)	19m 0s
linux-compiler-compat (clang-10)	18m 43s
linux-compiler-compat (gcc-4.8)	18m 11s
linux-compiler-compat (gcc-5)	18m 54s
linux-compiler-compat (gcc-6)	18m 36s
linux-compiler-compat (gcc-11)	19m 30s
linux-compiler-compat (gcc-13, --cmake-extra=-DCMAKE_EXE_LINKER_FLAGS="-lresolv")	20m 13s
linux-compiler-compat (clang-17)	20m 29s
linux-compiler-compat (gcc-7)	17m 52s
	10h 29m 12s

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