Added next release section to the changelog. [ci skip]
Added new options to Aws::S3::Encryption::Client#get_objet.

You can now pass the following options to `#get_object`:

* `:envelope_location`
* `:instruction_file_suffix`

Passing these options override the default values determined
during construction of the `Aws::S3::Encryption::Client`.
Updated links in README.