[book] Update book with ZSA changes #551

Job	Run time
Bitrot check	1m 36s
Book tests	1m 9s
Build target wasm32-unknown-unknown	1m 29s
Build target wasm32-wasi	1m 28s
Code coverage	3m 37s
Test on ubuntu-latest	10m 21s
Test on windows-latest	14m 11s
Test on i686-unknown-linux-gnu	21m 41s
Test on macOS-latest	8m 42s
Test on i686-unknown-linux-gnu with beta features	21m 57s
Test on ubuntu-latest with beta features	10m 19s
Test on i686-unknown-linux-gnu with nightly features	22m 34s
Test on windows-latest with beta features	13m 17s
Intra-doc links	1m 12s
Test on macOS-latest with beta features	8m 9s
Rustfmt	17s
Test on ubuntu-latest with nightly features	10m 34s
Test on windows-latest with nightly features	14m 8s
Test on macOS-latest with nightly features	8m 57s
	2h 55m 38s

Provide feedback