Release 2.15.0

What's Changed

• Fix minor errors in Mandarin tutorials by @wd929 in #187
• Update tts customization notebook to add emotion attribute by @mohnishparmar in #188
• nmt: synthetic data generation tutorial by @aishwaryac-nv in #186
• Update version.py by @rmittal-github in #189

New Contributors

• @aishwaryac-nv made their first contribution in #186

Full Changelog: r2.14.0...r2.15.0