fix doc

Signed-off-by: Qin Qin <qqin@google.com>

docs/root/configuration/http/http_filters/kill_request_filter.rst

@@ -4,7 +4,7 @@ Kill Request
 ===============
 
 The KillRequest filter can be used to crash Envoy when receiving a Kill request.
-By default, KillRequest filter is not built into Envoy binary since it is commmented out in *extensions_build_config.bzl*. If you want to use this extenstion, you need to uncomment it in *extensions_build_config.bzl*.
+By default, KillRequest filter is not built into Envoy binary since it is removed from *envoy_all_extensions()* in *all_extensions.bzl*. If you want to use this extenstion, please add it in *envoy_all_extensions()*.
 
 Configuration
 -------------
@@ -30,6 +30,7 @@ x-envoy-kill-request
 The following is an example configuration:
 
 .. code-block:: yaml
+
   name: envoy.filters.http.kill_request
   typed_config:
     "@type": type.googleapis.com/envoy.extensions.filters.http.kill_request.v3.KillRequest