create HTML for http-protocol.txt

./Documentation/technical/http-protocol.txt was missing from TECH_DOCS in Makefile.
Add it and also improve HTML formatting while still retaining good readability of the ASCII text:
- Use monospace font instead of italicized or roman font for machine output and source text
- Use roman font for things which should be body text
- Use double quotes consistently for "want" and "have" commands
- Use uppercase "C" / "S" consistently for "client" / "server";
  also use "C:" / "S:" instead of "(C)" / "(S)" for consistency and
  to avoid having formatted "(C)" as copyright symbol in HTML
- Use only spaces and not a combination of tabs and spaces for whitespace

Signed-off-by: Thomas Ackermann <th.acker@arcor.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/Makefile

@@ -60,7 +60,8 @@ SP_ARTICLES += howto/maintain-git
 API_DOCS = $(patsubst %.txt,%,$(filter-out technical/api-index-skel.txt technical/api-index.txt, $(wildcard technical/api-*.txt)))
 SP_ARTICLES += $(API_DOCS)
 
-TECH_DOCS = technical/index-format
+TECH_DOCS = technical/http-protocol
+TECH_DOCS += technical/index-format
 TECH_DOCS += technical/pack-format
 TECH_DOCS += technical/pack-heuristics
 TECH_DOCS += technical/pack-protocol