add release v0.6.3 release notes (#2536)

docs/release-notes/release-notes-0.6.3.md

@@ -0,0 +1,24 @@
+# DCRDEX v0.6.3
+
+This release contains several important fixes and improvements.  All users are advised to update.
+
+Please read the [v0.6.0 release notes](https://github.com/decred/dcrdex/releases/tag/v0.6.0) for a full list of changes since v0.5.
+
+## Features and Improvements
+- Trade limits scale with bond level.
+- Add **extension mode**. When in extension mode, 1 or more wallets are managed by a higher level application, and cannot be reconfigured through the dexc GUI.
+## Fixes
+- Fix bug where order was being retired before server accepted the `redeem` message.
+- Updates btcwallet dependency to incorporate recent upstream change (https://github.com/btcsuite/btcwallet/pull/870). Resolves a common error that arose during wallet rescans.
+- Resolves a potential server deadlock that can occur if processing of matched cancel orders result in an account cancel violation that would result in a suspension.
+- Removes "bonus tiers", which were an accounting curiosity on the server that didn't do anything for the client but did introduce a bug where client's bonds would fully expire before being replaced.
+
+## Code Summary
+25 files changed, 281 insertions(+), 126 deletions(-)
+
+https://github.com/decred/dcrdex/compare/v0.6.2...v0.6.3
+
+2 contributors
+
+- Brian Stafford (@buck54321)
+- Jonathan Chappelow (@chappjc)