fix(14.3-01): ship http body limits in examples/hello

- add examples/hello/config/http.yaml so serve, route:list and
  TestTypedItemRoute work without a manual config step
- drop the matching setup step and known-issue notes from README.md and
  docs/setup/installation.md

examples/hello/config/http.yaml

@@ -0,0 +1,5 @@
+body_limits:
+  # Request body limits in bytes, required by serve and route:list. Keep them
+  # YAML numbers: values from the environment are strings and are rejected.
+  default_bytes: 1048576
+  upload_bytes: 10485760