[Docs] Update README.md to be more accurate

[nottisa]

Thank you for submitting this pull request! We appreciate you spending the time to work on these changes.

What is the motivation?

I needed to quickly start using the Python driver. This documentation is flawed, and I realized I could very quickly fix it. This will save time for other developers like me.

Type of Change

• [X] Replaced all references to SurrealDB and AsyncSurrealDB with Surreal
• [X] Added the use function for connecting to namespaces and databases
• [X] Fixed connection strings to properly reference the /rpc route rather than /database/namespace

What does this change do?

These changes make it easier for people to quickly start writing code with the Surreal Python driver.

• [X] I have read the Contributing Guidelines