docs: Add more HTTPS proxy documentation

- Document HTTPS proxy type.

- Document --write-out %{proxy_ssl_verify_result}.

- Document SOCKS proxy + HTTP/HTTPS proxy combination.

HTTPS proxy support was added in 7.52.0 for OpenSSL, GnuTLS and NSS.

Ref: https://github.com/curl/curl/commit/cb4e2be

2 files changed, 35 insertions, 12 deletions

diff --git a/docs/libcurl/opts/CURLOPT_PROXY.3 b/docs/libcurl/opts/CURLOPT_PROXY.3
index 9a8656114..65f84f528 100644
--- a/docs/libcurl/opts/CURLOPT_PROXY.3
+++ b/docs/libcurl/opts/CURLOPT_PROXY.3
@@ -38,10 +38,22 @@ option \fICURLOPT_PROXYPORT(3)\fP. If not specified, libcurl will default to
 using port 1080 for proxies.
 
 The proxy string may be prefixed with [scheme]:// to specify which kind of
-proxy is used. Use socks4://, socks4a://, socks5:// or socks5h:// (the last
-one to enable socks5 and asking the proxy to do the resolving, also known as
-\fICURLPROXY_SOCKS5_HOSTNAME\fP type) to request the specific SOCKS version to
-be used. No scheme specified or http://, will be treated as HTTP proxies.
+proxy is used.
+
+.RS
+.IP http://
+HTTP Proxy. Default when no scheme or proxy type is specified.
+.IP https://
+HTTPS Proxy. (Added in 7.52.0 for OpenSSL, GnuTLS and NSS)
+.IP socks4://
+SOCKS4 Proxy.
+.IP socks4a://
+SOCKS4a Proxy. Proxy resolves URL hostname.
+.IP socks5://
+SOCKS5 Proxy.
+.IP socks5h://
+SOCKS5 Proxy. Proxy resolves URL hostname.
+.RE
 
 Without a scheme prefix, \fICURLOPT_PROXYTYPE(3)\fP can be used to specify
 which kind of proxy the string identifies.
diff --git a/docs/libcurl/opts/CURLOPT_PROXYTYPE.3 b/docs/libcurl/opts/CURLOPT_PROXYTYPE.3
index d2d924257..19856195e 100644
--- a/docs/libcurl/opts/CURLOPT_PROXYTYPE.3
+++ b/docs/libcurl/opts/CURLOPT_PROXYTYPE.3
@@ -28,15 +28,26 @@ CURLOPT_PROXYTYPE \- proxy protocol type
 
 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXYTYPE, long type);
 .SH DESCRIPTION
-Pass a long with this option to set type of the proxy. Available options for
-this are \fICURLPROXY_HTTP\fP, \fICURLPROXY_HTTP_1_0\fP
-\fICURLPROXY_SOCKS4\fP, \fICURLPROXY_SOCKS5\fP, \fICURLPROXY_SOCKS4A\fP and
-\fICURLPROXY_SOCKS5_HOSTNAME\fP. The HTTP type is default.
+Pass one of the values below to set the type of the proxy.
 
-If you set \fICURLOPT_PROXYTYPE(3)\fP to \fICURLPROXY_HTTP_1_0\fP, it will
-only affect how libcurl speaks to a proxy when CONNECT is used. The HTTP
-version used for "regular" HTTP requests is instead controlled with
-\fICURLOPT_HTTP_VERSION(3)\fP.
+.RS
+.IP CURLPROXY_HTTP
+HTTP Proxy. Default.
+.IP CURLPROXY_HTTPS
+HTTPS Proxy. (Added in 7.52.0 for OpenSSL, GnuTLS and NSS)
+.IP CURLPROXY_HTTP_1_0
+HTTP 1.0 Proxy. This is very similar to CURLPROXY_HTTP except it uses HTTP/1.0
+for any CONNECT tunnelling. It does not change the HTTP version of the actual
+HTTP requests, controlled by \fICURLOPT_HTTP_VERSION(3)\fP.
+.IP CURLPROXY_SOCKS4
+SOCKS4 Proxy.
+.IP CURLPROXY_SOCKS4A
+SOCKS4a Proxy. Proxy resolves URL hostname.
+.IP CURLPROXY_SOCKS5
+SOCKS5 Proxy.
+.IP CURLPROXY_SOCKS5_HOSTNAME
+SOCKS5 Proxy. Proxy resolves URL hostname.
+.RE
 
 Often it is more convenient to specify the proxy type with the scheme part of
 the \fICURLOPT_PROXY(3)\fP string.