Update core po files with renamed page (sysadmin#17736)

The wiki/src/install/inc/steps/reporting.inline.html file was moved to wiki/src/doc/first_steps/start/reporting.inline.mdwn in c25952a3, but the list of core po files was not updated accordingly.

This caused a breakage of the Translation Platform's cron.sh script, in the part where it updates Weblate components based in the list of core po files (sysadmin#17736 (closed)).

This commit only updates said list with the new entry and should be enough to fix the problem.