Pass through a few of the new pluginOptions added to gatsby-theme-brain

[aengusmcmillin]

I have added some functionality recently to gatsby-theme-brain that might be useful here. This PR passes through the parameters to enable that support

A couple of things:

• You can now limit to only a certain set of file types to be processed
• You can declare additional note types and a corresponding template to render some notes differently
• Hashtags can be linkified, so #Books could turn into a link to a Books page
• You can now hide the square brackets from those links. It will turn [[Books]] into [Books](bookspageurl)

[aravindballa]

Thanks so much! ❤️