doc: documented how to build this module as a dymamic module.

README.md

@@ -14,6 +14,7 @@ Table of Contents
     * [modular](#modular)
     * [auto-generated & easily extensible](#auto-generated--easily-extensible)
 * [Usage for users](#usage-for-users)
+    * [Building as a dynamic module](#building-as-a-dynamic-module)
 * [Usage for developers](#usage-for-developers)
     * [Warning: using NDK_ALL](#warning-using-ndk_all)
 * [TODO](#todo)
@@ -94,6 +95,19 @@ e.g.
 
 [Back to TOC](#table-of-contents)
 
+Building as a dynamic module
+----------------------------
+
+Starting from NGINX 1.9.11, you can also compile this module as a dynamic module, by using the `--add-dynamic-module=PATH` option instead of `--add-module=PATH` on the
+`./configure` command line above. And then you can explicitly load the module in your `nginx.conf` via the [load_module](http://nginx.org/en/docs/ngx_core_module.html#load_module)
+directive, for example,
+
+```nginx
+load_module /path/to/modules/ndk_http_module.so;
+```
+
+[Back to TOC](#table-of-contents)
+
 Usage for developers
 ====================