MINOR: add nbconn option in bind #447

Job	Run time
generate-models	1m 24s
generate-specification	44s
HAProxy check commit message	0s
golangci-lint	1m 19s
lint-spec	7s
go mod tidy	6s
Build	22s
Tests	2m 52s
e2e on HAProxy (2.1)	48s
e2e on HAProxy (2.2)	43s
e2e on HAProxy (2.3)	40s
e2e on HAProxy (2.4)	40s
e2e on HAProxy (2.5)	40s
e2e on HAProxy (2.6)	39s
e2e on HAProxy (2.7)	40s
e2e on HAProxy (2.8)	47s
	12m 31s

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