[openssl/openssl] 22fa16: quic http3 demo: minor updates

[James Muir]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 22fa1602da91af2194997e0576582bb4f0cdd7e0
      https://github.com/openssl/openssl/commit/22fa1602da91af2194997e0576582bb4f0cdd7e0
  Author: James Muir <james at openssl.org>
  Date:   2023-11-08 (Wed, 08 Nov 2023)

  Changed paths:
    M demos/http3/Makefile
    M demos/http3/README.md

  Log Message:
  -----------
  quic http3 demo: minor updates

-update run command to include LD_LIBRARY_PATH
-suggest installing libnghttp3-dev on Ubuntu
-drop "-f" from clean recipe (it is already included in $(RM))

Part of https://github.com/openssl/project/issues/253

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22623)