Make non-item pages of the wiki available

[flbraun]

Currently the search index only knows about item pages, but it would be beneficial to also have access to pages that explain game mechanics or contain meta information, e.g.:

• https://www.poewiki.net/wiki/Evasion
• https://www.poewiki.net/wiki/Fossil
• https://www.poewiki.net/wiki/Delirium_league

Find a way to aggregate them (Cargo API, scraping, hand-curated list?) into the data files. Changes in the Electron app should not be required for this.