existing wiki paged cannot be added from the edition

[federicocalvo]

Description of the issue

When you want to add wiki page to the sidebars, you can't call it from the selector

https://user-images.githubusercontent.com/7256766/139920784-1d2796ff-b0fe-462a-ac6e-9ce3af9a5542.mov

Context information (for bug reports)

Editing any wiki page to be able to edit the siderbar

Output of bench version

Frappe Version 13.11
ERPNext Version 13.11
Wiki Version 1.0.0 branch version-13