Improve raw-stream example

[rafd]

Minor tweak to :raw-stream? example to prevent future readers from following the example directly and ending up with a program that creates a connection-pool on every request (...eventually consuming all threads on the OS).

[kachayev]

Good catch @rafd, thanks! def also would not work for applications, as you need something like components to manage resources properly. Tho' I agree it's still less harmful compared to current version.

[kachayev]

There's another connection pool (in the same file) created the same way. Let me update the PR.