use internal link to Instructor Notes

Author: tobyhodges

_extras/guide.md

@@ -8,7 +8,7 @@ ____
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 ## Making a handout
 
-Librarians like handouts. To make a handout for this lesson, adapt/print from [https://librarycarpentry.org/lc-data-intro-archives/reference/](https://librarycarpentry.org/lc-data-intro-archives/reference/).
+Librarians like handouts. To make a handout for this lesson, adapt/print from [the lesson reference page]({{page.root}}/reference.html).
 
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 ## 02-jargon-busting.md