doc: replace `maddyctl` with `maddy`

[pouriya]

There are 4 uses of maddyctl inside dist/apparmor/dev.foxcpp.maddyctl and 2 inside internal/cli/app.go. I was not sure that I should remove/replace them too or not so I did not touch them.

[foxcpp]

dist/apparmor/dev.foxcpp.maddyctl can be removed altogether.

internal/cli/app.go should not be touched for at least one release - this is a backward-compatibility hack that makes maddy pretend to be maddyctl if it is symlinked as one.

[pouriya]

Done

[pouriya]

Should I remove this line or we need to create a link for at least one release?

[pouriya]

ping