Issues with labs/introduction

[jweeks2023]

https://github.com/princomp/princomp.github.io/blob/c3c4fb718277f70da37d2a693f2533b70bd51637/source/labs/Introduction.md?plain=1#L12-L14

These links do not actually redirect to the corresponding sections in the page.

https://github.com/princomp/princomp.github.io/blob/c3c4fb718277f70da37d2a693f2533b70bd51637/source/labs/Introduction.md?plain=1#L59

Same as above

https://github.com/princomp/princomp.github.io/blob/c3c4fb718277f70da37d2a693f2533b70bd51637/source/labs/Introduction.md?plain=1#L105

Same as above

[aubertc]

This whole lab probably deserves a rewriting.