Update changelog for 3.9.0 (#1053)

* add link to Atlas Search Indexes page

* note availability in Docker Hub

* note VERSIONINFO

* note requirement of C driver 1.25.0

* note dropped OSs

* remove whitespace change

* remove parenthetical

For consistency with other reference to C driver. C driver consists of libmongoc and libbson.

* Note availability on vcpkg and Conan

* note behavior of `MONGOCXX_OVERRIDE_DEFAULT_INSTALL_PREFIX`

* fix comment in CMake script

Author: kevinAlbs

CHANGELOG.md

@@ -9,17 +9,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- The C++ driver container image is now available on [Docker hub](https://hub.docker.com/r/mongodb/mongo-cxx-driver).
+- Document availability of on [vcpkg](https://vcpkg.io/) and [Conan](https://conan.io/center/recipes/mongo-cxx-driver).
 - Add CMake option `MONGOCXX_OVERRIDE_DEFAULT_INSTALL_PREFIX` (default is `TRUE`
-  for backwards-compatibility).
-- Add API to manage Atlas Search Indexes.
+  for backwards-compatibility). If enabled, `CMAKE_INSTALL_PREFIX` defaults to the build directory.
+- Add API to manage [Atlas Search Indexes](https://www.mongodb.com/docs/atlas/atlas-search/).
 - Automatically download C driver dependency if not provided.
+- Add VERSIONINFO resource to bsoncxx.dll and mongocxx.dll.
 
 ### Changed
 - Do not build tests as part of `all` target. Configure with `BUILD_TESTING=ON` to build tests.
 - Bump minimum required CMake version to 3.15 to support the FetchContent module and for consistency with the C Driver.
 - Improve handling of downloaded (non-system) mnmlstc/core as the polyfill library.
   - Use `FetchContent` instead of `ExternalProject` to download and build the library.
   - Do not patch include directives in mnmlstc/core headers.
+- Bump minimum C Driver version to [1.25.0](https://github.com/mongodb/mongo-c-driver/releases/tag/1.25.0).
 
 ### Fixed
 - Explicitly document that throwing an exception from an APM callback is undefined behavior.
@@ -28,3 +32,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 - Remove support for exported targets from the CMake project build tree.
+- Drop support for the following operating systems:
+  - macOS 10.14 and 10.15
+  - Ubuntu 14.04

CMakeLists.txt

@@ -206,7 +206,7 @@ if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT AND MONGOCXX_OVERRIDE_DEFAULT_INS
     message(WARNING
         "mongocxx: The default CMAKE_INSTALL_PREFIX is being overridden to the "
         "build directory. This behavior will not be the default in a future "
-        "release. Build with 'MONGOCXX_OVERRIDE_DEFAULT_INSTALL_PREFIX=ON' to opt "
+        "release. Build with 'MONGOCXX_OVERRIDE_DEFAULT_INSTALL_PREFIX=OFF' to opt "
         "into what will be the default behavior in a future release. Setting install "
         "path to: ${CMAKE_BINARY_DIR}/install")
     set(CMAKE_INSTALL_PREFIX "${CMAKE_BINARY_DIR}/install" CACHE PATH "default install path" FORCE)