[DOC] Stakeholder-specific getting started materials

[cjnolet]

cuVS has 3 mean types of users:

1. Library developers (usually Python for data analysis).
2. Lower-level database developers
3. Higher-level end-users

Currently, the getting started materials and documentation try to cater to everyone, but it makes the materials more confusing for each one of the user types listed above. We should have stakeholder-specific sections in our docs that appear specifically those 3 types of users.

This is also going to be important for the NVIDIA cuVS developer page to differentiate the different user types and provide them with a more customized getting started experimence.