Remove false warning about copying the log config to a homeserver.yaml (#11092)

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

changelog.d/11092.doc

+Clarify the the sample log config can be copied from the documentation without issue.

docs/usage/configuration/logging_sample_config.md

@@ -2,13 +2,13 @@
 
 Below is a sample logging configuration file. This file can be tweaked to control how your
 homeserver will output logs. A restart of the server is generally required to apply any
-changes made to this file.
+changes made to this file. The value of the `log_config` option in your homeserver
+config should be the path to this file.
 
-Note that the contents below are *not* intended to be copied and used as the basis for
-a real homeserver.yaml. Instead, if you are starting from scratch, please generate
-a fresh config using Synapse by following the instructions in
-[Installation](../../setup/installation.md).
+Note that a default logging configuration (shown below) is created automatically alongside
+the homeserver config when following the [installation instructions](../../setup/installation.md).
+It should be named `<SERVERNAME>.log.config` by default.
 
 ```yaml
 {{#include ../../sample_log_config.yaml}}
-```
\ No newline at end of file
+```