docs: Update Example_Configs.md to note that baud should be 250000

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

Author: KevinOConnor

docs/Example_Configs.md

@@ -101,6 +101,9 @@ is also a useful resource for finding and sharing config files.
    For example, a config should not specify a custom
    `max_extrude_cross_section`. Do not enable debugging features. For
    example there should not be a `force_move` config section.
+10. All known boards that Klipper supports can use the default serial
+    baud rate of 250000. Do not recommend a different baud rate in an
+    example config file.
 
 Example config files are submitted by creating a github "pull
 request". Please also follow the directions in the