Add notice to package maintainers on readme

[bovine3dom]

Our versioning system is a bit weird and the poor arch maintainer gets the package flagged out of date often when it isn't actually out of date

https://aur.archlinux.org/packages/firefox-tridactyl-native

1. the latest version on this repository is meaningless alone

2. the native/current_version file on the Tridactyl repo is the version that that commit supports

3. check the commit that the beta was built at for the beta build

4. check the tag to find the version for stable Tridactyl