Add requestHeaders, fixes #11

Author: nfour

README.md

@@ -276,9 +276,9 @@ responseModels:
   application/xml: "CreateResponseXML"
 ```
 
-##### `responseHeaders`
+##### `responseHeaders` and `requestHeaders`
 
-The `responseHeaders` section of the configuration allows you to define the HTTP response headers for the function event.
+The `responseHeaders/requestHeaders` section of the configuration allows you to define the HTTP response headers for the function event.
 
 The attributes for a response header are as follow:
 
@@ -292,6 +292,11 @@ responseHeaders:
     description: "Content Type header"
     schema:
       type: "string"
+requestHeaders:
+  - name: "Content-Type"
+    description: "Content Type header"
+    schema:
+      type: "string"
 ```
 
 ## Example configuration