Updates to get tutorial ready for the workshop

[laduplessis]

Some updates to try to get the tutorial ready for the workshop.

Changes

• Add some metadata to the README.md file so it can be displayed on the website
• Edit the bibtex file so the website compilation doesn't crash when parsing it
• Edit language/style of the tutorial
• Checked the tutorial up to importing data.

Required changes
These issues need to be corrected before the tutorial can be uploaded to the website.

• I couldn't manage to import the continuous data into BEAUti2
• I couldn't run the included xml files (class contraband.app.beauti.ContinuousData could not be found). I have installed contraband v1.0.1. It looks like there are changes to the contraband code, but no new release.
• There are no precooked runs included.