Merge #9866: Document increase in memory usage due to mempool/dbcache sharing

50ae5c7 Document increase in memory usage due to mempool/dbcache sharing (Matt Corallo)

Tree-SHA512: e52a310a5ac1f94b30f367a7bf514b2cf0724530102953eef7f7c7e00a067db568b5e1b51129dfdb1a237e016c7a8b01cc6da8c06a24ab5b970c43d045adb204

doc/release-notes.md

@@ -348,6 +348,16 @@ Fundrawtransaction change address reuse
 - Users should also consider using `getrawchangeaddress()` in conjunction
   with `fundrawtransaction`'s `changeAddress` option.
 
+Unused mempool memory used by coincache
+----------------------------------------
+
+- Before 0.14, memory reserved for mempool (using the `-maxmempool` option)
+  went unused during initial block download, or IBD. In 0.14, the UTXO DB cache
+  (controlled with the `-dbcache` option) borrows memory from the mempool
+  when there is extra memory available. This may result in an increase in
+  memory usage during IBD for those previously relying on only the `-dbcache`
+  option to limit memory during that time.
+
 0.14.0 Change log
 =================