Serve song sheets from folder

[ruthmoog]

Investigate if possible to pick up song sheet PDFs from a folder and parse into the HTML served up.

This would,

• automate the lyrics mark-up for easy maintenance
• allow Cleo to easily add or remove content to the songbook

[ruthmoog]

https://quii.gitbook.io/learn-go-with-tests/go-fundamentals/html-templates

Review templating and look at serving files from a directory within the repo