Update the list of headers that get stripped when caching is enabled for Azure Frontdoor profiles

Author: gball14

articles/frontdoor/front-door-caching.md

@@ -169,6 +169,8 @@ Cache-Control response headers that indicate that the response won't be cached s
 The following request headers won't be forwarded to a backend when using caching.
 - Content-Length
 - Transfer-Encoding
+- Accept
+- Accept-Charset
 - Accept-Language
 
 ## Response headers