TODO README:

• Add requirements (and link to instructions to install them)
  • gcc >= ?
  • g++ >= ?
  • postgres >= ?
  • cmake >= ?
  • make >= ?
• Add instructions for installing pgvector
• No instructions for Windows (my machine)
• Fix README implicit references to postgres / toolchain which aren't addressed
  • Example: CREATE EXTENSION lanterndb; should be run in postgres, but there is no mention of it.
• Add tech stack to README? (Which version of C/C++/Rust is being used)