Clarify HPKE example #1082

Job	Run time
build_python_27 (ubuntu-22.04, yes)	2m 46s
build_python_27 (ubuntu-22.04, no)	2m 41s
build_python_27 (windows-latest, yes)	3m 50s
build_python_27 (windows-latest, no)	3m 45s
test_c_linux (0, x64)	57s
test_c_linux (0, x32)	1m 10s
python_no_gil	5m 34s
mypy	18s
test_c_linux (1, x32)	1m 17s
build (3.8, yes, ubuntu-22.04)	2m 28s
test_c_windows (win32)	43s
build (3.7, no, ubuntu-22.04)	2m 37s
test_c_linux (1, x64)	59s
build (3.8, no, ubuntu-22.04)	2m 33s
build (3.10, no, ubuntu-22.04)	4m 44s
build (3.9, yes, ubuntu-22.04)	4m 58s
build (3.7, yes, ubuntu-22.04)	2m 40s
build (3.9, no, ubuntu-22.04)	4m 59s
build (3.11, no, ubuntu-22.04)	4m 31s
build (3.13, yes, macos-13)	4m 36s
build (3.12, yes, ubuntu-22.04)	4m 32s
build (3.13, no, ubuntu-22.04)	4m 43s
build (3.13, yes, ubuntu-22.04)	4m 21s
build (3.11, yes, ubuntu-22.04)	4m 27s
build (3.12, no, ubuntu-22.04)	4m 34s
build (3.13, no, windows-latest)	4m 13s
build (3.13, yes, windows-latest)	4m 11s
build (3.10, yes, ubuntu-22.04)	4m 49s
build (3.13, yes, ubuntu-22.04-arm)	6m 50s
build (pypy3.9, no, ubuntu-latest)	3m 59s
build (pypy2.7, no, ubuntu-latest)	1m 36s
test_c_windows (x64)	37s
	1h 46m 58s

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