DOC: server: Add docs for "server" and "default-server" new "no-*" and other settings.

DOC: server: Add docs for "server" and "default-server" new "no-*" and other settings.

New boolean settings have been added to disable others. Most of them have "no-" as prefix.

"enabled" disables "disabled" setting,
"no-agent-check" disables "agent-check",
"no-backup" disables "backup",
"no-check" disables "check",
"no-check-ssl" disables "check-ssl",
"no-force-sslv3" disables "force-sslv3",
"no-force-tlsv10" disables "force-tlsv10",
"no-force-tlsv11" disables "force-tlsv11",
"no-force-tlsv12" disables "force-tlsv12,
"no-send-proxy" disables "send-proxy",
"no-send-proxy-v2" disables "send-proxy-v2",
"no-send-proxy-v2-ssl" disables "send-proxy-v2-ssl",
"no-send-proxy-v2-ssl-cn" disables "send-proxy-v2-ssl-cn",
"no-ssl" disables "ssl",
"no-verifyhost" disables "verifyhost",
"sslv3" disables "no-sslv3",
"ssl-reuse" disables "no-ssl-reuse",
"stick" disables "non-stick",
"tlsv10" disables "no-tlsv10",
"tlsv11" disables "no-tlsv11",
"tlsv12" disables "no-tlsv12",
"tls-tickets" disables "no-tls-tickets".

Settings with arguments are now supported on "default-server" lines:

"addr", "ca-file", "ciphers", "crl-file", "crt", "cookie", "namespace", "observe",
"redir", "sni", "source", "tcp-ut" and "track".

From now on, all server "settings" including the new ones above are supported by
"default-server" except "id" which is only supported on "server" lines.