Add base documentation for evp_test tool #97

Job	Run time
cygwin (windows-2019, win64, -DCMAKE_C_COMPILER=gcc --strict-warnings enable-demos no-fips)	31m 57s
minimal (windows-2019)	8m 36s
minimal (windows-2022)	9m 26s
plain (windows-2019)	17m 49s
plain (windows-2022)	17m 20s
shared (windows-2019, win64, enable-fips)	19m 50s
shared (windows-2019, win32, --strict-warnings no-fips)	28m 41s
shared (windows-2022, win64, enable-fips)	25m 33s
shared (windows-2022, win32, --strict-warnings no-fips)	23m 54s
	3h 3m 6s

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