add permalink for locally-built site homepage

Author: tobyhodges

index.md

@@ -1,11 +1,11 @@
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 layout: lesson
 root: .
+permalink: index.html
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 This Library Carpentry lesson introduces archivists to working with data. At the conclusion of the lesson you will: be able to explain terms, phrases, and concepts in code or software development; identify and use best practice in data structures; use regular expressions in searches.
 
 > ## Prerequisites
 >
 > This lesson has no prerequisites. Ideally you will need a laptop and an internet connection, though this is not required.
 {: .prereq}
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