update readme redner config helper

NEWS.rst

@@ -5,6 +5,8 @@
 18.0.1.7.0
 ----------
 
+Update Redner config parameter names in the README
+
 Add more export formats from Typst
 
 18.0.1.6.0

README.rst

@@ -46,8 +46,8 @@
 
 Once your account is ready, configure the module with the following ``ir.config_parameter``::
 
-  rednerd.server_url = https://redner.orbeet.io
-  rednerd.api_key = <your API key here>
+  redner.server_url = https://redner.orbeet.io
+  redner.api_key = <your API key here>
   redner.account = <your account name>
   redner.timeout = 20