Add additional information to the README

* expand on docker instructions
* identify API documentation
* identify WASM documentation

Acked-by: Andrew Clayton <a.clayton@nginx.com>
Signed-off-by: Ava Hahn <a.hahn@f5.com>

README.md

@@ -42,12 +42,22 @@ For details and available language packages, see the
 
 ``` console
 $ docker pull unit
+$ mkdir /tmp/unit-control # customize as needed.
+$ docker run -d \
+      --mount type=bind,src=/tmp/unit-control,dst=/var/run \
+      --mount type=bind,src=.,dst=/www \
+      --network host \
+      unit
 ```
 
 For a description of image tags, see the
 [docs](https://unit.nginx.org/installation/#docker-images).
 
 
+Your current working directory will now be mounted to the Unit image at `/www`.
+You can reach its socket at `/tmp/unit-control/control.unit.sock` assuming no 
+further customizations have been made.
+
 ### Amazon Linux, Fedora, Red Hat
 
 ``` console
@@ -71,6 +81,15 @@ $ wget https://raw.githubusercontent.com/nginx/unit/master/tools/setup-unit && c
 For details and available language packages, see the
 [docs](https://unit.nginx.org/installation/#official-packages).
 
+## Configuration
+
+NGINX Unit provides a RESTful API for dynamic configuration.
+See the [control API documentation](https://unit.nginx.org/controlapi/)
+for more information on what endpoints are available and how to use them.
+
+
+For full details of configuration management, see the
+[docs](https://unit.nginx.org/configuration/#configuration-management).
 
 ## Running a Hello World App
 
@@ -161,8 +180,10 @@ Unit's output should contain both snippets, neatly organized:
 }
 ```
 
-For full details of configuration management, see the
-[docs](https://unit.nginx.org/configuration/#configuration-management).
+## WebAssembly
+Unit supports running WebAssembly Components (WASI 0.2).
+For more information see the
+[Unit Configuration Docs](https://unit.nginx.org/configuration/#configuration-wasm).
 
 ## OpenAPI Specification