From Fedora Project Wiki
This template records what is considered to be the 'current' Fedora test compose or release candidate. It is updated automatically by relval when the compose sub-command is used with the --current option. It can be edited by hand so long as the format is kept (the content that is transcluded should be a simple text string of the format 'releaseversion milestone compose', e.g. '21 Beta RC3').
It can be used in various ways; relval report-results uses it to guess the compose for which the user most likely wants to report results, and the validation testing instruction template uses it to display a note on result pages that are not for the current compose, warning that they are not for the current compose and linking to it.