Add release version (7.72.0) for the method variables from the writeout option (-w)

[cbarange]

Hello,

I was using the curl write-out option with variable %{method} as I saw in this documentation. And My curl version didn't support this variable so I take time to find out from which version this variable comme from and I found inside the change log that the %{method} variable was added in 7.72.0 (https://curl.se/changes.html)

So I think it can help people to add this information to this very use and useful documentation.

PS: I didn't build the project after editing the file; I didn't find any information about it, so hope I did great.

Thanks you, clement.

[bagder]

Thanks!