add two examples: quaint pooled + tokio-postgres with tls

[Weakky]

Overview

Two examples added: quaint pooled + tokio-postgres with TLS.

Observations so far: TLS is what adds most of the overhead compared to tokio-postgres without TLS.

Numbers are roughly:

• Pooled: 700ms
• Tokio-postgres with TLS: 650ms (among which connect_tls from tokio-postgres takes up to ~330ms)