Example uses deprecated HTTP v2

[DifferentialOrange]

tracing/README.md

Lines 241 to 313 in 9feeae6

	```lua
	#!/usr/bin/env tarantool
	local http_server = require('http.server')
	local http_router = require('http.router')
	local fiber = require('fiber')
	local log = require('log')
	local zipkin = require('zipkin.tracer')
	local opentracing = require('opentracing')
	local app = {}
	local Sampler = {
	sample = function() return true end,
	}
	local HOST = '0.0.0.0'
	local PORT = '33302'
	local function handler(req)
	-- Extract content from request's http headers
	local ctx, err = opentracing.http_extract(req:headers())
	if ctx == nil then
	local resp = req:render({ text = err })
	resp.status = 400
	return resp
	end
	local hello_to = req:query_param('helloto')
	-- Start new child span
	local span = opentracing.start_span_from_context(ctx, 'format_string')
	-- Set service type
	span:set_component('formatter')
	span:set_server_kind()
	span:set_http_method(req:method())
	span:set_http_path(req:path())
	local greeting = span:get_baggage_item('greeting')
	local result = ('%s, %s!'):format(greeting, hello_to)
	local resp = req:render({ text = result })
	-- Simulate long request processing
	fiber.sleep(2)
	span:log_kv({
	event = 'String format',
	value = result,
	})
	resp.status = 200
	span:set_http_status_code(resp.status)
	span:finish()
	return resp
	end
	function app.init()
	-- Initialize zipkin client that will be send spans every 5 seconds
	local tracer = zipkin.new({
	base_url = 'localhost:9411/api/v2/spans',
	api_method = 'POST',
	report_interval = 5,
	on_error = function(err) log.error(err) end,
	}, Sampler)
	opentracing.set_global_tracer(tracer)
	local httpd = http_server.new(HOST, PORT)
	local router = http_router.new()
	:route({ path = '/format', method = 'GET' }, handler)
	httpd:set_router(router)
	httpd:start()
	end
	app.init()
	return app
	```

and

tracing/README.md

Lines 317 to 382 in 9feeae6

	#!/usr/bin/env tarantool
	local http_server = require('http.server')
	local http_router = require('http.router')
	local fiber = require('fiber')
	local log = require('log')
	local zipkin = require('zipkin.tracer')
	local opentracing = require('opentracing')
	local app = {}
	local Sampler = {
	sample = function() return true end,
	}
	local HOST = '0.0.0.0'
	local PORT = '33303'
	local function handler(req)
	local ctx, err = opentracing.http_extract(req:headers())
	if ctx == nil then
	local resp = req:render({ text = err })
	resp.status = 400
	return resp
	end
	local hello = req:query_param('hello')
	local span = opentracing.start_span_from_context(ctx, 'print_string')
	span:set_component('publisher')
	span:set_server_kind()
	span:set_http_method(req:method())
	span:set_http_path(req:path())
	-- Simulate long request processing
	fiber.sleep(3)
	io.write(hello, '\n')
	local resp = req:render({text = '' })
	resp.status = 200
	span:set_http_status_code(resp.status)
	span:finish()
	return resp
	end
	function app.init()
	local tracer = zipkin.new({
	base_url = 'localhost:9411/api/v2/spans',
	api_method = 'POST',
	report_interval = 5,
	on_error = function(err) log.error(err) end,
	}, Sampler)
	opentracing.set_global_tracer(tracer)
	local httpd = http_server.new(HOST, PORT)
	local router = http_router.new()
	:route({ path = '/print', method = 'GET' }, handler)
	httpd:set_router(router)
	httpd:start()
	end
	app.init()
	return app
	```

use HTTP v2 module, which is deprecated now (tarantool/http#142). HTTP v1 is installed by default from servers and, since v1 and v2 code is incompatible, example fails. It confuses users trying to run code from README (https://t.me/tarantoolru/182158).