[doc] 31829 release note

doc/release-notes-31829.md

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+P2P
+
+- The transaction orphanage, which holds transactions with missing inputs temporarily while the node attempts to fetch
+its parents, now has improved Denial of Service protections. Previously, it enforced a maximum number of unique
+transactions (default 100, configurable using `-maxorphantx`). Now, its limits are as follows: the number of entries
+(unique by wtxid and peer), plus each unique transaction's input count divided by 10, must not exceed 3,000. The total
+weight of unique transactions must not exceed 404,000 Wu multiplied by the number of peers.
+
+- The `-maxorphantx` option no longer has any effect, since the orphanage no longer limits the number of unique
+transactions. Users should remove this configuration option if they were using it, as the setting will cause an
+error in future versions when it is no longer recognized.