Move some changelog entries from 0.3.0 to 0.4.0 #3097

Job	Run time
Book tests	13s
Bitrot check	2m 5s
Latest build on ubuntu-latest	49s
Latest build on windows-latest	2m 33s
Build target wasm32-wasi	1m 34s
Code coverage	8m 39s
Latest build on macOS-latest	2m 31s
Intra-doc links	2m 17s
Rustfmt	12s
Test on ubuntu-latest	8m 8s
Test on windows-latest	8m 44s
Test on macOS-latest	10m 27s
	48m 12s

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