capi: updated comments in gen_header.sh #2375

Job	Run time
Verify hyper.h is up to date	28s
Check Style	11s
Check MSRV	20s
Test C API (FFI)	24s
minimal-versions	26s
features	23s
Test with Miri	1m 1s
udeps	31s
Test stable on ubuntu-latest	1m 12s
Test stable on windows-latest	1m 58s
Test stable on macOS-latest	1m 59s
Test beta on ubuntu-latest	1m 14s
Test beta on windows-latest	1m 49s
Test beta on macOS-latest	2m 23s
Test nightly on ubuntu-latest	1m 30s
Test nightly on windows-latest	2m 30s
Test nightly on macOS-latest	2m 59s
Build docs	25s
Check exposed types	14s
CI is green	1s
	21m 58s

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