Create "Onboarding Guide"

[25ohms]

1. Explain what we are doing + research proposal
2. Current state of progress/ what's left to fo
3. Overview of tasks and timeline (timeline can be rough)
   ^ condensed :3

Update root README.md with setup instructions

• add links to all our resources
• incuding google drive folder
• research proposal
• notebook LM with all our literature sources

[SteveAndCow]

from main branch, can remove

• salami_data_public

• spectrogram_generation

• music-files

• keep open-source-models and songformer-integration from songformer-testing branch