clarify install instructions

[andrisi]

The homepage notes about installation for Ubuntu: "Who knows when Ubuntu will add Nchan to their repository?..." - but it's already there in the Ubuntu repo. There problem is that it is likely an outdated version as the nchan_stub_status page does not contain a version number, a feature that was supposed to be there since 1.1.5. We're at version 1.2.* so this is old. The .deb packages offered migh be ninary incompatible with the current mainlin or stable version from nginx.org repos. Please clarify this in the docs.

[andrisi]

Since I built the latest from source it works flawlessly. I know it is like a "marketing issue" but having an outdated version in the official repos is doing a big disservice for your great work.

[catwell]

FYI I checked today and Jammy (22.04 LTS) ships nchan 1.2.7 in the libnginx-mod-nchan package.