Clarify replay behavior

The current wording makes it seem like you can apply source-level changes and have them work with replayed data, and this is not true. This PR is a partner to #1375

Author: c-noonan

src/guides/what-is-replay.md

@@ -17,7 +17,7 @@ This means you can send a limited sample of your data to a new tool to test it o
 
 ## Replays for resilience
 
-With Replays, you're protected from outages and errors.  If a destination which you rely on experiences an outage, or temporarily isn't able to accept incoming data, you can use Replays to re-send data to that tool once the service recovers. You can also use Replays to recover from errors caused by misconfigurations in your Segment systems - sending data in the wrong format, or want to apply [destination filters](/docs/connections/destinations/destination-filters/)? Change your mapping, clear out the bad data, and replay it from the source. You can also use this to update the schema in your data warehouse when it changes.
+With Replays, you're protected from outages and errors.  If a destination which you rely on experiences an outage, or temporarily isn't able to accept incoming data, you can use Replays to re-send data to that tool once the service recovers. You can also use Replays to recover from errors caused by misconfigurations in your Segment systems - sending data in the wrong format, or want to apply [destination filters](/docs/connections/destinations/destination-filters/)? Change your mapping using a destination filter, clear out the bad data, and replay it to that destination. You can also use this to update the schema in your data warehouse when it changes.
 
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