Add SNI check env var docs (#37793)

* Add SNI check env var

* Update environment-variables.md

* Update docs/configuring-metabase/environment-variables.md

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

---------

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

docs/configuring-metabase/environment-variables.md

@@ -1325,6 +1325,14 @@ Since: v42.0
 
 Set the system files channel used by Metabase to store images. This channel has to be public, and is not intended to be used by humans. The Slack App has to be invited into this channel.
 
+### `MB_JETTY_SKIP_SNI`
+
+Type: string<br>
+Default: `"true"`<br>
+Since: v48.4
+
+Setting `MB_JETTY_SKIP_SNI=true` (the default setting) turns off the Server Name Indication (SNI) checks in the Jetty web server. Normally you would leave this enabled. If, however, you're terminating the Transport Layer Security (TLS) connection on Metabase itself, and you're getting an error like `HTTP ERROR 400 Invalid SNI`, consider either setting `MB_JETTY_SKIP_SNI=false`, or use another SSL certificate that exactly matches the domain name of the server.
+
 ### `MB_SOURCE_ADDRESS_HEADER`
 
 Type: string<br>