Feature summary:
Alias Special:UndeletePage to Special:Undelete
Use case(s):
DeletePage is aliased to Delete, so it makes sense for similar aliasing to Special:Undelete.
A user might type the wrong name.
Good first task
There's only a minor change required here to languages / messages / MessagesEn.php to add these aliases. It's literally a change to one line of code to add it to the array:
'Undelete' => [ 'Undelete' ],
Currently at line 548 to:
'Undelete' => [ 'Undelete', 'UndeletePage' ],