docs: Add `HTTP headers` guide #706

Job	Run time
PR title check	4s
Checks / Package check	33s
Checks / Spell check	7s
Checks / Actions lint check	32s
Checks / Doc check / Docs check	1m 53s
Checks / Type check / Type check (3.14)	35s
Checks / Type check / Type check (3.13)	32s
Checks / Type check / Type check (3.12)	33s
Checks / Type check / Type check (3.10)	31s
Checks / Type check / Type check (3.11)	31s
Checks / Lint check / Lint check (3.13)	33s
Checks / Lint check / Lint check (3.14)	34s
Checks / Lint check / Lint check (3.10)	34s
Checks / Lint check / Lint check (3.12)	33s
Checks / Lint check / Lint check (3.11)	34s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.14)	4m 6s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.13)	5m 24s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.11)	5m 0s
Checks / Unit tests / Unit tests (windows-latest, 3.13)	6m 31s
Checks / Unit tests / Unit tests (macos-latest, 3.10)	6m 5s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.10)	5m 10s
Checks / Unit tests / Unit tests (windows-latest, 3.10)	7m 22s
Checks / Unit tests / Unit tests (windows-latest, 3.11)	6m 18s
Checks / Unit tests / Unit tests (windows-latest, 3.14)	6m 33s
Checks / Unit tests / Unit tests (macos-latest, 3.12)	4m 15s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.12)	6m 2s
Checks / Unit tests / Unit tests (windows-latest, 3.12)	7m 9s
Checks / Unit tests / Unit tests (macos-latest, 3.13)	6m 27s
Checks / Unit tests / Unit tests (macos-latest, 3.14)	4m 38s
Checks / Unit tests / Unit tests (macos-latest, 3.11)	5m 34s
	1h 35m 13s

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