add additional clarifications

src/ipips/ipip-0484.md

@@ -78,10 +78,11 @@ Even though existing transfer protocol names start with `transport`, e.g. `trans
 ## Design rationale
 
 - Using these query parameters improves cache efficiency, as the response will be smaller and more specific to the client's needs.
-- Backward compatibility by not changing the default behavior of the API.
-- Use of protocol name rather than code makes it easier for human debugging.
+- Backward compatibility is maintained by not changing the default behavior of the API.
+- Use of protocol name rather than codes makes it easier for human debugging.
 - DHT providers currently do not contain any transfer protocol information. `unknown` can be passed to `filter-protocols` to include such providers.
 - Since provider records are independent of peer records, and it's pretty common to have provider records without up-to-date multiaddrs for that peer, `unknown` can be passed to `filter-addrs` to include such providers.
+- Combining transfer protocol and transport protocol filters is done by ANDing the results of the filters, e.g. `?filter-addrs=webtransport&filter-protocols=transport-bitswap` will return providers that support bitswap and have a webtransport multiaddr.
 
 ### User benefit