feat: support for `[[wikilinks]]` as an optional initializer

[jaredcwhite]

In order to enable support for wiki-like content sources (aka an Obsidian content vault), we should support the wikilinks syntax. I've already written a plugin for a wiki-type site, so copying that over as a first-party solution won't be difficult. I'm thinking folks can just add

init :wikilinks

to the config/initializers.rb file and boom. This would be useful in conjunction with #515, #884, etc.