add v1.40.2 release note

Author: c9s

doc/release/v1.40.2.md

@@ -0,0 +1,13 @@
+## Fixes
+
+- Fixed pivot high indicator (used low, sorry :p)
+
+## Minor Features
+
+- Added G-H filter and Kalman filter.
+- Write strategy config into the backtest report directory.
+
+[Full Changelog](https://github.com/c9s/bbgo/compare/v1.40.1...main)
+
+ - [#918](https://github.com/c9s/bbgo/pull/918): feature: write strategy config in the backtest report directory
+ - [#915](https://github.com/c9s/bbgo/pull/915): feature: add G-H filter and Kalman filter