add to README.md

README.md

@@ -165,6 +165,7 @@ options:
   --execution-provider {cpu} [{cpu} ...]                   available execution provider (choices: cpu, ...)
   --execution-threads EXECUTION_THREADS                    number of execution threads
   --headless                                               run in headless mode
+  --enhancer-upscale-factor                                Sets the upscale factor for the enhancer. Only applies if `face_enhancer` is set as a frame-processor
   -v, --version                                            show program's version number and exit
 ```