Obsolete installation instructions of plug-ins for DNF v. 4

[Ricky-Tigg]

Hello. Installation instructions of plug-ins for DNF v. 4 became obsolete in the dnf-plugins-extras repository's README-md.

$ dnf -q list dnf-plugin-\
{kickstart,rpmconf,showvars,snapper,torproxy,tracer}
No matching packages to list

Are still provided by source RPM dnf-plugins-extras

$ dnf -q list --available python3-dnf-plugin-\
{kickstart,rpmconf,showvars,snapper,torproxy,tracer}
python3-dnf-plugin-kickstart.noarch 4.1.2-11.fc44 fedora
python3-dnf-plugin-rpmconf.noarch   4.1.2-11.fc44 fedora
python3-dnf-plugin-showvars.noarch  4.1.2-11.fc44 fedora
python3-dnf-plugin-snapper.noarch   4.1.2-11.fc44 fedora
python3-dnf-plugin-torproxy.noarch  4.1.2-11.fc44 fedora
python3-dnf-plugin-tracer.noarch    4.1.2-11.fc44 fedora