Add project introduction #1750

Job	Run time
check	1m 19s
cross x86_64-unknown-linux-gnu (stable)	2m 6s
cross x86_64-unknown-linux-gnu (beta)	2m 7s
cross x86_64-unknown-linux-gnu (nightly)	1m 51s
cross x86_64-unknown-linux-musl (stable)	2m 10s
cross aarch64-unknown-linux-gnu (stable)	2m 16s
cross aarch64-unknown-linux-musl (stable)	2m 29s
fuzz record_ref	6m 55s
fuzz select_query	9m 17s
test x86_64-unknown-linux-gnu (stable)	2m 10s
test x86_64-unknown-linux-gnu (beta)	2m 57s
test x86_64-unknown-linux-gnu (nightly)	2m 5s
test x86_64-apple-darwin (stable)	3m 5s
test x86_64-apple-darwin (beta)	3m 30s
test x86_64-apple-darwin (nightly)	3m 43s
test x86_64-pc-windows-gnu (stable)	4m 12s
test i686-pc-windows-msvc (stable)	4m 26s
book	4m 10s
deny	1m 35s
clippy	1m 3s
audit	0s
fmt	23s
miri	2m 20s
upgrades	0s
gh-pages	0s
	1h 6m 9s

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