[ releases notes ] Updated agda-releases file

The version from the master branch was copied in the maint-2.4.2
branch.
[ releases notes ] Added step related to the bug tracker
[ releases notes ] The standard library is not released with Agda
[ releases notes ] Choosing the right branch of the standard library
[ releases notes ] Create Everything.agda in the standard library
[ releases notes ] Added .md extension
[ releases notes ] Adding second source-repository in .cabal
[ releases notes ] Tagging after running `cabal check`
[ releases notes ] Running the test-suite

I followed the approach used in agda-releases.
[ releases notes ] Cleaning
[ releases notes ] Latest steps

Update the Agda Wiki and announce the release.
[ releases notes ] Removing second source-repository in .cabal
[ releases notes ] Turning -Werror back on
[ releases notes ] Updating version in interaction test cases
[ releases notes ] Fixed documentation
[ releases notes ] Updated date