Use correct account creation function

If you use `NewAccount` console says there is no such function

docs/_interface/Managing-your-accounts.md

@@ -143,7 +143,7 @@ Creates a new account and prints the address.
 On the console, use:
 
 ```
-> personal.NewAccount()
+> personal.newAccount()
 ... you will be prompted for a password ...
 
 or