http3.md: mention how the fallback can be h1 or h2

Closes #14736
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Daniel Stenberg 2024-08-30 09:04:15 +02:00
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@ -20,14 +20,16 @@ Example:
# `--http3`
Attempt HTTP/3 to the host in the URL, but fallback to earlier HTTP versions
if the HTTP/3 connection establishment fails. HTTP/3 is only available for
HTTPS and not for HTTP URLs.
if the HTTP/3 connection establishment fails or is slow. HTTP/3 is only
available for HTTPS and not for HTTP URLs.
This option allows a user to avoid using the Alt-Svc method of upgrading to
HTTP/3 when you know that the target speaks HTTP/3 on the given host and port.
HTTP/3 when you know or suspect that the target speaks HTTP/3 on the given
host and port.
When asked to use HTTP/3, curl issues a separate attempt to use older HTTP
versions with a slight delay, so if the HTTP/3 transfer fails or is slow, curl
still tries to proceed with an older HTTP version.
still tries to proceed with an older HTTP version. The fallback performs the
regular negoatiaion between HTTP/1 and HTTP/2.
Use --http3-only for similar functionality *without* a fallback.