add documentation

docs/user-guide/annotations.md

@@ -58,6 +58,7 @@ The following annotations are supported:
 |[nginx.ingress.kubernetes.io/upstream-hash-by](#custom-nginx-upstream-hashing)|string|
 |[nginx.ingress.kubernetes.io/upstream-vhost](#custom-nginx-upstream-vhost)|string|
 |[nginx.ingress.kubernetes.io/whitelist-source-range](#whitelist-source-range)|CIDR|
+|[nginx.ingress.kubernetes.io/proxy-buffering](#proxy-buffering)|string|
 
 **Note:** all the values must be a string. In case of booleans or number it must be quoted.
 
@@ -406,3 +407,15 @@ To use custom values in an Ingress rule define these annotation:
 ```yaml
 nginx.ingress.kubernetes.io/proxy-body-size: 8m
 ```
+
+### Proxy buffering
+
+Enable or disable proxy buffering [`proxy_buffering`](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffering).
+By default proxy buffering is disabled in the nginx config.
+
+To configure this setting globally for all Ingress rules, the `proxy-buffering` value may be set in the NGINX ConfigMap.
+To use custom values in an Ingress rule define these annotation:
+
+```yaml
+nginx.ingress.kubernetes.io/proxy-buffering: "on"
+```

docs/user-guide/configmap.md

@@ -126,6 +126,7 @@ The following table shows a configuration option's name, type, and the default v
 |[limit‑rate](#limit-rate)|int|0|
 |[limit‑rate‑after](#limit-rate-after)|int|0|
 |[http‑redirect‑code](#http-redirect-code)|int|308|
+|[proxy‑buffering](#proxy-buffering)|string|"off"|
 
 ## add-headers
 
@@ -698,3 +699,7 @@ Default code is 308.
 Why the default code is 308?
 
 [RFC 7238](https://tools.ietf.org/html/rfc7238) was created to define the 308 (Permanent Redirect) status code that is similar to 301 (Moved Permanently) but it keeps the payload in the redirect. This is important if the we send a redirect in methods like POST.
+
+## proxy-buffering
+
+Enables or disables [buffering of responses from the proxied server](http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffering).