fix chunked output

README.md

@@ -248,7 +248,7 @@ request->send(response);
 ### Chunked Response
 Used when content length is unknown. Works best if the client supports HTTP/1.1
 ```cpp
-AsyncWebServerResponse *response = request->beginChunkedResponse("text/plain", [](uint8_t buffer, size_t maxLen) -> size_t {
+AsyncWebServerResponse *response = request->beginChunkedResponse("text/plain", [](uint8_t *buffer, size_t maxLen) -> size_t {
   //Write up to "maxLen" bytes into "buffer" and return the amount written.
   //You will be asked for more data until 0 is returned
   //Keep in mind that you can not delay or yield waiting for more data!

src/WebResponses.cpp

@@ -252,7 +252,7 @@ size_t AsyncAbstractResponse::_ack(AsyncWebServerRequest *request, size_t len, u
       char pre[6];
       sprintf(pre, "%x\r\n", readLen);
       size_t preLen = strlen(pre);
-      memmove(buf+preLen, buf, preLen);
+      memmove(buf+preLen, buf, readLen);
       for(size_t i=0; i<preLen; i++)
         buf[i] = pre[i];
       outLen = preLen + readLen;