[doc] Add pre_dv area to directory structure doc
Fix #1306
Signed-off-by: Michael Schaffner <msf@google.com>
diff --git a/doc/ug/directory_structure.md b/doc/ug/directory_structure.md
index 2ab979d..772d734 100644
--- a/doc/ug/directory_structure.md
+++ b/doc/ug/directory_structure.md
@@ -49,6 +49,9 @@
│ │
│ ├──model => Reference 'model' implementation in C (if applicable)
│ │
+ │ ├──pre_dv => This is a work area for experimental DV work that is worthy of
+ │ │ maintaining, but not intended to apply towards code coverage.
+ │ │
│ ├──rtl => RTL design sources
│ │
│ ├──util => IP-specfic automation scripts (if applicable)