docs(logger): adds back warning of custom logger

Adds back in a small portion of commit #a70b7a36b6d5571390fdb489370490709a31ad0c
that warns when a custom logger is used and `logger: false` is set,
that Nest cannot use the custom logger for the instantiation of the
server.

fix #1270

Author: jmcdo29

content/techniques/logger.md

@@ -135,6 +135,8 @@ Here we use the `get()` method on the `NestApplication` instance to retrieve the
 
 You can also inject this `MyLogger` provider in your feature classes, thus ensuring consistent logging behavior across both Nest system logging and application logging. See <a href="techniques/logger#using-the-logger-for-application-logging">Using the logger for application logging</a> below for more information.
 
+The only downside of this solution is that your first initialization messages won't be handled by your logger instance, though, it shouldn't really matter at this point.
+
 #### Using the logger for application logging
 
 We can combine several of the techniques above to provide consistent behavior and formatting across both Nest system logging and our own application event/message logging. In this section, we'll achieve this with the following steps: