Remove obsolete book `Makefile` and `edithtml.sh` #4008

Job	Run time
Bitrot check	1m 35s
Book tests	3m 52s
Build target wasm32-unknown-unknown	3m 54s
Build target wasm32-wasi	3m 56s
Code coverage	21m 32s
Intra-doc links	3m 50s
Rustfmt	17s
Test on ubuntu-latest	3m 49s
Test on i686-unknown-linux-gnu	4m 18s
Test on windows-latest	3m 50s
Test on i686-unknown-linux-gnu with beta features	4m 11s
Test on i686-unknown-linux-gnu with nightly features	4m 1s
Test on macOS-latest	3m 51s
Test on ubuntu-latest with beta features	3m 47s
Test on windows-latest with beta features	3m 51s
Test on macOS-latest with beta features	3m 51s
Test on ubuntu-latest with nightly features	3m 54s
Test on windows-latest with nightly features	3m 53s
Test on macOS-latest with nightly features	3m 50s
	1h 26m 2s

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