message: Added release notes for C++
diff: # Release History
  -## 1.0.0-beta.2 (Unreleased)
  +## 1.0.0-beta.2 (2020-10-09)
  +### Breaking Changes
  +
  +- Throw Azure::Http::TransportException if creating new connection fails.
  +- Response objects store Nullable\<T\>.
  +
  +### Bug Fixes
  +
  +- Switched to a more stable wait on sockets to address connection timeouts.
  +- Replace `Nullable(const T&)` with `Nullable(T)` to avoid extra copy when initialized with an rvalue.
  +
  +### Other changes and Improvements
  +
  +- Improved performance on windows when using libcurl.
  +- Pinned the version of package dependencies.
  +- Added NOTICE.txt for 3rd party dependencies.
  ## 1.0.0-beta.1 (2020-09-09)
  - Initial release
  -
  