Correct documentation about config_opts: remove MFA info.

Author: Pat Maddox

lib/prom_ex/config.ex

@@ -154,10 +154,8 @@ defmodule PromEx.Config do
       read/write access to a directory in order to download and copy the GrafanaAgent binary. This is the
       full path to that directory.
 
-    * `:config_opts` - The configuration file that GrafanaAgent is started with. This option
-      can either accept an MFA that will return a string of the full path where the YAML configuration
-      file is, or a keyword list with options so that PromEx can generate a config file for you. If you
-      take the route where PromEx generates a config file for you, you must provide the following
+    * `:config_opts` - The configuration file that GrafanaAgent is started with. This is a keyword list
+      with options so that PromEx can generate a config file for you. You must provide the following
       options:
 
       * `:metrics_server_path` - The path where the Prometheus metrics are exposed.