add 1.15.1 release notes (#1048)

Author: kevinAlbs

CHANGELOG.md

@@ -10,6 +10,14 @@
   - This applies to IntelDFP when `MONGOCRYPT_DFP_DIR` is not set to `USE-SYSTEM`.
   - Note: `FetchContent_Populate()` is still used for CMake versions prior to 3.18 to avoid `add_subdirectory()` behavior.
 
+## 1.15.1
+
+### Fixed
+- Fix possible error when text options include multiple query types and are used for a find payload: `Text search query specification cannot contain multiple query type specifications`.
+- Require setting contention for text options.
+- Improve error message if text options are unset when using text algorithm.
+
+
 ## 1.15.0
 
 ### New features