docs: indicate http.sslCertType and sslKeyType

These useful config options were added in 0a01d41 (http: add
support for different sslcert and sslkey types., 2023-03-20) but
lacked documentation.

Signed-off-by: Andrew Carter <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: plentydone

Documentation/config/http.txt

@@ -216,6 +216,18 @@ http.sslBackend::
 	This option is ignored if cURL lacks support for choosing the SSL
 	backend at runtime.
 
+http.sslCertType::
+	Type of client certificate used when fetching or pushing over HTTPS.
+	(e.g. "PEM", "DER", or "P12"). See also libcurl `CURLOPT_SSLCERTTYPE`
+	Can be overridden by the `GIT_SSL_CERT_TYPE` environment variable.
+
+http.sslKeyType::
+	Type of client private key used when fetching or pushing over HTTPS.
+	(e.g. "PEM", "DER", or "ENG"). Particularly useful when set to "ENG"
+	for authenticating with PKCS#11 tokens. See also libcurl
+	`CURLOPT_SSLCERTTYPE` . Can be overridden by the `GIT_SSL_KEY_TYPE`
+	environment variable.
+
 http.schannelCheckRevoke::
 	Used to enforce or disable certificate revocation checks in cURL
 	when http.sslBackend is set to "schannel". Defaults to `true` if