Update libcurl

Engine/lib/curl/docs/cmdline-opts/proxy.d

@@ -0,0 +1,48 @@
+c: Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Long: proxy
+Short: x
+Arg: [protocol://]host[:port]
+Help: Use this proxy
+Category: proxy
+Example: --proxy http://proxy.example $URL
+Added: 4.0
+See-also: socks5 proxy-basic
+---
+Use the specified proxy.
+
+The proxy string can be specified with a protocol:// prefix. No protocol
+specified or http:// will be treated as HTTP proxy. Use socks4://, socks4a://,
+socks5:// or socks5h:// to request a specific SOCKS version to be used.
+(Added in 7.21.7)
+
+Unix domain sockets are supported for socks proxy. Set localhost for the host
+part. e.g. socks5h://localhost/path/to/socket.sock
+
+HTTPS proxy support via https:// protocol prefix was added in 7.52.0 for
+OpenSSL, GnuTLS and NSS.
+
+Unrecognized and unsupported proxy protocols cause an error since 7.52.0.
+Prior versions may ignore the protocol and use http:// instead.
+
+If the port number is not specified in the proxy string, it is assumed to be
+1080.
+
+This option overrides existing environment variables that set the proxy to
+use. If there's an environment variable setting a proxy, you can set proxy to
+"" to override it.
+
+All operations that are performed over an HTTP proxy will transparently be
+converted to HTTP. It means that certain protocol specific operations might
+not be available. This is not the case if you can tunnel through the proxy, as
+one with the --proxytunnel option.
+
+User and password that might be provided in the proxy string are URL decoded
+by curl. This allows you to pass in special characters such as @ by using %40
+or pass in a colon with %3a.
+
+The proxy host can be specified the same way as the proxy environment
+variables, including the protocol prefix (http://) and the embedded user +
+password.
+
+If this option is used several times, the last one will be used.