Extend examples for the Postgres input connector

[zxqfd555]

Is your feature request related to a problem? Please describe.
Currently, the Postgres input connector has examples that use an int as a primary key. Common use cases also include using a string or a uuid as a primary key. Adding these would improve the onboarding process for connector users.

Describe the solution you'd like
Several additional examples:

• Primary key is a string;
• Primary key is a UUID;
• Primary key is composite.