Update -> upgrade

README.md

@@ -9,7 +9,7 @@ Lichess bot interface for uci compatible engines.
 - Put bot name, api key and engine path in `config.toml`
 - Run with `./lichess-bot config.toml`
 
-### Update to bot account
+### Upgrade to bot account
 As well are normal usage shown about, you can use this library to upgrade your account
 > WARNING: Upgrading your account cannot be undone
 To upgrade run like this