Small improvements to protocol documentation (#15460) #10176

Job	Run time
Test suite with Python nightly	18m 1s
Test mypyc suite with 32-bit Python	10m 25s
Test suite with py37-windows-64	26m 54s
Test suite with py38-ubuntu	20m 54s
Test suite with py39-ubuntu	21m 20s
Test suite with py37-ubuntu, mypyc-compiled	20m 50s
Test suite with py310-ubuntu, mypyc-compiled	19m 36s
Test suite with py310-ubuntu	21m 43s
Test suite with py311-ubuntu, mypyc-compiled	23m 27s
mypyc runtime tests with py37-macos	7m 21s
mypyc runtime tests with py37-debug-build-ubuntu	8m 22s
Type check our own code (py37-ubuntu)	2m 5s
Type check our own code (py37-windows-64)	3m 4s
Formatting with Black + isort and code style with flake8	1m 34s
	3h 25m 36s

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