[TT-14489] Update documentation for master - Gateway 5.8.1 (#6335)

Import config/docs

Co-authored-by: mativm02 <83959431+mativm02@users.noreply.github.com>
(cherry picked from commit a928334)

Author: 2 people

tyk-docs/content/shared/gateway-config.md

@@ -213,13 +213,16 @@ Enabled WebSockets and server side events support
 ENV: <b>TYK_GW_HTTPSERVEROPTIONS_CERTIFICATES</b><br />
 Type: `CertsData`<br />
 
-Deprecated. SSL certificates used by Gateway server.
+Deprecated: Use `ssl_certificates`instead.
 
 ### http_server_options.ssl_certificates
 ENV: <b>TYK_GW_HTTPSERVEROPTIONS_SSLCERTIFICATES</b><br />
 Type: `[]string`<br />
 
-SSL certificates used by your Gateway server. A list of certificate IDs or path to files.
+Index of certificates available to the Gateway for use in client and upstream communication.
+The string value in the array can be two of the following options:
+1. The ID assigned to and used to identify a certificate in the Tyk Certificate Store
+2. The path to a file accessible to the Gateway. This PEM file must contain the private key and public certificate pair concatenated together.
 
 ### http_server_options.server_name
 ENV: <b>TYK_GW_HTTPSERVEROPTIONS_SERVERNAME</b><br />