A Wiki Page’s name is configured in the large property shown at the top of the Wiki Page Designer, below the toolbar:
Provision of a name is mandatory, and the value provided may be a maximum of 100 characters. The Wiki page’s name is the same as the filename under which it is saved within the RPI file system. As such, it must be unique amongst the Wiki pages in the folder within which saved.
You can edit a Wiki page’s name by clicking the property. Complete the edit by clicking off the property, or by hitting return.