Fix "Search" Application description

Summary:
This description was somehow broken since 2019:

{F276845}

Probably this was caused by a Remarkup breaking change introduced by this
specific XSS security fix:

rP54bcbdaba94a: Fix an XSS issue with certain high-priority remarkup rules embedded inside…

Maybe in the future the backtick operator will be supported again
in Remarkup. Or, maybe not. So, let's just workaround to make that
specific page "less exploded" again.

Closes T15230

Test Plan:

• visit the page /applications/view/PhabricatorSearchApplication/
• check that now the Remarkup is rendered perfectly

Reviewers: O1 Blessed Committers, Cigaryno, avivey

Reviewed By: O1 Blessed Committers, Cigaryno, avivey

Subscribers: avivey, speck, tobiaswiese, Matthew, Cigaryno

Maniphest Tasks: T15230

Differential Revision: https://we.phorge.it/D25110