Fix small typo in EdDSA docs #767

Job	Run time
mypy	15s
build_python_27 (ubuntu-20.04, yes)	5m 43s
build_python_27 (ubuntu-20.04, no)	2m 50s
build (3.5, yes, ubuntu-20.04)	2m 50s
build_python_27 (windows-latest, yes)	6m 1s
build (3.5, no, ubuntu-20.04)	2m 54s
test_c_linux (0, x64)	1m 40s
build_python_27 (windows-latest, no)	4m 35s
test_c_linux (0, x32)	2m 13s
build (3.6, yes, ubuntu-20.04)	2m 56s
test_c_linux (1, x64)	1m 22s
test_c_windows (x64)	1m 0s
build (3.6, no, ubuntu-20.04)	3m 42s
test_c_linux (1, x32)	1m 52s
test_c_windows (win32)	1m 23s
build (3.7, yes, ubuntu-20.04)	2m 55s
build (3.7, no, ubuntu-20.04)	3m 11s
build (3.8, yes, ubuntu-20.04)	2m 38s
build (3.8, no, ubuntu-20.04)	2m 40s
build (3.9, yes, ubuntu-20.04)	2m 35s
build (3.9, no, ubuntu-20.04)	3m 1s
build (3.10, yes, ubuntu-20.04)	2m 32s
build (3.10, no, ubuntu-20.04)	2m 47s
build (3.11, yes, ubuntu-20.04)	2m 12s
build (3.11, no, ubuntu-20.04)	2m 17s
build (3.12-dev, yes, ubuntu-20.04)	2m 34s
build (3.12-dev, no, ubuntu-20.04)	3m 1s
build (3.11, yes, macos-12)	3m 30s
build (3.11, no, windows-latest)	5m 20s
build (3.11, yes, windows-latest)	5m 4s
build (3.12-dev, no, windows-latest)	6m 10s
build (3.12-dev, yes, windows-latest)	6m 16s
build (pypy2.7, no, ubuntu-latest)	1m 51s
build (pypy3.9, no, ubuntu-latest)	2m 5s
	1h 43m 55s

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