NIC: Add nginx.org/upstream-vhost annotation

content/nic/configuration/ingress-resources/advanced-configuration-with-annotations.md

@@ -135,6 +135,7 @@ The table below summarizes the available annotations.
 | *nginx.org/rewrites* | N/A | Configures URI rewriting using [proxy_pass](https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass) directive. | N/A | [rewrites](https://github.com/nginx/kubernetes-ingress/tree/v{{< nic-version >}}/examples/ingress-resources/rewrites) |
 | *nginx.org/rewrite-target* | N/A | Configures URI rewriting using the [rewrite](https://nginx.org/en/docs/http/ngx_http_rewrite_module.html#rewrite) directive. The annotation value specifies the target path that requests should be rewritten to. Supports regex capture groups (`$1`, `$2`, etc.) when used with `nginx.org/path-regex`. Mutually exclusive with `nginx.org/rewrites`. | N/A | [rewrite-target](https://github.com/nginx/kubernetes-ingress/tree/v{{< nic-version >}}/examples/ingress-resources/rewrite-target) |
 |*nginx.org/proxy-set-headers* | N/A | Enables customization of proxy headers and values using the [proxy_set_header](https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_set_header) directive. Example: `"nginx.org/proxy-set-headers": "header-a: valueA,header-b: valueB,header-c: valueC"` | N/A | [Proxy Set Headers](https://github.com/nginx/kubernetes-ingress/tree/v{{< nic-version >}}/examples/ingress-resources/proxy-set-headers). |
+| *nginx.org/upstream-vhost* | N/A | Sets the `Host` header sent to the upstream to a fixed hostname, using the [proxy_set_header](https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_set_header) directive (or [grpc_set_header](https://nginx.org/en/docs/http/ngx_http_grpc_module.html#grpc_set_header) for gRPC backends). When not set, the upstream receives the Host header from the original request. Only a literal hostname is accepted; NGINX variables are not supported. | N/A | *example.internal* [upstream-vhost](https://github.com/nginx/kubernetes-ingress/tree/v{{< nic-version >}}/examples/ingress-resources/upstream-vhost) |
 | *nginx.org/add-header* | *add-header* | Adds one or more response headers with the [add_header](https://nginx.org/en/docs/http/ngx_http_headers_module.html#add_header) directive. Use the format `Header-Name: value[:always]` and separate entries with commas. | N/A | *X-Frame-Options: DENY: always, X-Content-Type-Options: nosniff* |
 | *nginx.org/add-header-inherit* | *add-header-inherit* | Controls how [add_header_inherit](https://nginx.org/en/docs/http/ngx_http_headers_module.html#add_header_inherit) applies inherited response headers. Allowed values are `on`, `off`, and `merge`. | N/A | *merge* |
 | *nginx.org/proxy-redirect-from* | N/A | The `redirect` parameter for [proxy_redirect](https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_redirect). Accepts `off`, `default`, a URL string, or a regex prefixed with `~` (case-sensitive) or `~*` (case-insensitive). Requires `nginx.org/proxy-redirect-to` when value is a URL or regex. | N/A | *http://redirect-backend-svc/v1/* or *off* |