docs: adjust role name

Author: saitho

README.md

@@ -7,7 +7,7 @@ StackHead module for using Nginx as webserver.
 Install it via `ansible-galaxy`:
 
 ```
-ansible-galaxy install getstackhead.stackhead_module_webserver_nginx
+ansible-galaxy install getstackhead.stackhead_webserver_nginx
 ```
 
 In order to use Nginx with [StackHead](https://get.stackhead.io), set `stackhead__webserver` it in your inventory file:
@@ -18,7 +18,7 @@ In order to use Nginx with [StackHead](https://get.stackhead.io), set `stackhead
 all:
   vars:
     # Use Nginx as webserver
-    stackhead__webserver: getstackhead.stackhead_module_webserver_nginx
+    stackhead__webserver: getstackhead.stackhead_webserver_nginx
   hosts:
     myserver:
       ansible_host: 123.456.789 # ...