Add smol-rs logo to docs #556

Job	Run time
clippy	32s
msrv (ubuntu-latest, 1.63)	34s
msrv (windows-latest, 1.63)	1m 4s
cross (ubuntu-latest)	2m 17s
cross (macos-latest)	54s
fmt	17s
security_audit	40s
test (ubuntu-latest, nightly)	1m 5s
test (ubuntu-latest, beta)	1m 3s
test (ubuntu-latest, stable)	1m 27s
test (windows-latest, nightly)	2m 8s
test (windows-latest, beta)	1m 59s
test (windows-latest, stable)	2m 1s
test (macos-latest, nightly)	2m 15s
test (macos-latest, beta)	1m 36s
test (macos-latest, stable)	2m 4s
windows_gnu (nightly, x86_64-pc-windows-gnu)	2m 1s
	23m 57s

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