Documentation updates

• Added a guide for using Neon with Koyeb, which is a serverless platform designed to easily deploy applications globally.
• Added Retool to our list of GUI applications and clients that support connecting to Neon.
• Updated the Vercel guide to include the following topics:
  • Add the Neon Vercel Integration to another Vercel project
  • Use the Neon integration
  • Connect Vercel and Neon manually
• Updated the How to use connection pooling documentation with information about how to enable pooling by adding a -pooler suffix to the compute endpoint ID in your connection string. This feature allows you to connect to the same database with pooled and non-pooled connections.
• Added descriptions for Operation, Project, Branch, and Endpoint properties to the Neon API reference.
• Updated the Neon documentation to reflect the renaming of Users to Roles in the Neon Console.