diff --git a/README.adoc b/README.adoc
index 4bd887f658ba..eca5e657ba97 100644
--- a/README.adoc
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@@ -10,7 +10,7 @@ The documentation is sourced in http://www.methods.co.nz/asciidoc/[AsciiDoc] and
 
 == Repo Organization
 
-Each directory of the repo represents a different collection of topics (you can think of directories as books). The exception is the `build_system` directory, which contains the code used to generate the finished documentation. Within each 'book' directory, topics exist as separate asciidoc files and an `images` directory contains any images that are included in the topics.
+Each directory of the repo represents a different collection of topics (you can think of directories as books). The exceptions to this rule are directories whose names start with an underscore (like `_builder_lib` and `_javascripts`), which contain the assets used to generate the finished documentation. Within each 'book' directory, topics exist as separate asciidoc files and an `images` directory contains any images that are included in the topics.
 
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