Added changelog

(cherry picked from commit dca71ec)

Author: batconjurer

.changelog/unreleased/improvements/4776-query-conversions-requires-masp-epoch.md

@@ -0,0 +1,12 @@
+- Querying the conversion state becomes more difficult as nodes progress
+  to higher and higher epochs. For instance, on a mainnet clone running on
+  accelerated epochs, client queries for conversions always timeout (even after
+  modifying timeout_broadcast_tx_commit) when the node goes beyond a certain
+  MASP epoch. This happens because the conversion state grows linearly with
+  the MASP epoch counter. This PR attempts to address this problem by making
+  the conversions RPC endpoint require that clients specify the MASP epoch
+  they want conversions from. This implies two things: first the size of the
+  response from the conversions RPC endpoint should now be constant (equal to
+  the number of tokens in the shielded rewards program), and second a client
+  requiring all conversions now has to do a separate query for each MASP epoch.
+  ([\#4776](https://github.com/namada-net/namada/pull/4776))