Docker image doesn't have the tex packages needed to render PDF

[Code0x58]

As can be seen by using the running the example template and choosing to render a PDF while using the docker-compose setup from #14

[jonbannister]

Internally we use:

               texlive-ec \
               texlive-collection-fontsrecommended \
               texlive-collection-latexrecommended \
               texlive-collection-xetex \
               texlive-texconfig \
               texlive-xetex-def \
               texlive-adjustbox \
               texlive-upquote \
               texlive-ulem 

This may be a superset of what's required but may get us across the line.