Update README, docs, and manifest #12

Job	Run time
Test / x86_64-pc-windows-msvc	39s
Clippy	18s
Format	10s
Test / x86_64-pc-windows-msvc --release	39s
Doc	19s
Miri /	34s
Toolchain / stable	18s
Miri / --release	38s
Cross / i686-unknown-linux-gnu	1m 8s
Toolchain / stable --release	13s
Cross / i586-unknown-linux-gnu	1m 10s
Toolchain / beta	17s
Cross / armv7-unknown-linux-gnueabihf	1m 7s
Toolchain / beta --release	14s
Features /	19s
Cross / aarch64-unknown-linux-gnu	1m 8s
Toolchain / nightly	15s
Features / simdutf8 uuid	16s
Cross / thumbv6m-none-eabi	1m 10s
Toolchain / nightly --release	14s
Features / derive	13s
Features / derive simdutf8 uuid	17s
Features / std	17s
Features / std simdutf8 uuid	16s
Features / std derive	15s
Features / std derive simdutf8 uuid	14s
	12m 38s

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