Improve http cache header

Author: zamronypj

working-with-response/http-cache-header/index.md

@@ -32,10 +32,13 @@ When this middleware attached to route, additional steps is taken:
 - If method is not cacheable (not GET nor HEAD) then nothing is done else,
 - `Cache-Control` header is added to response header,
 - If ETag is used then MD5 hash of response body is computed and `ETag` header is added to response with hash value of response body.
-- If request contains `If-None-Match` header, its value is compared with ETag value, if they are matched or `If-Non-Match` equals `"*"`, then response is considered not modified.
-- If response contains header `Last-Modified` and request contains header `If-Modified-Since`, both headers values are compared. If `Last-Modified` is older then response is considered not modified.
+- If request contains `If-None-Match` header, its value is compared with ETag value, if they are matched or `If-None-Match` equals `"*"`, then response is considered not modified.
+- If ETag comparison return false and response contains header `Last-Modified` and request contains header `If-Modified-Since`, both headers values are compared. If `Last-Modified` is older then response is considered not modified.
 - If response is not modified, instance `TNotModifiedResponse` is returned instead. Read [Not modified response](/working-with-response#not-modified-response) section for more information this class.
 
+Read [source code](https://github.com/fanoframework/fano/blob/master/src/Middleware/BuiltIns/CacheControlMiddlewareImpl.pas)
+if you want to know more.
+
 ## Setting Cache-Control header value
 
 ### Set type