adding buildnotes
diff --git a/bundles/org.eclipse.wst.html.ui/buildnotes_html.html b/bundles/org.eclipse.wst.html.ui/buildnotes_html.html
index 2cff2d3..2baca38 100644
--- a/bundles/org.eclipse.wst.html.ui/buildnotes_html.html
+++ b/bundles/org.eclipse.wst.html.ui/buildnotes_html.html
@@ -23,7 +23,8 @@
M3, 02/23/2005</h2>
<h3>What's new in this drop</h3>
-<p>Added HTML validation, which validates against HTML spec 4.01 (with a few small variations), for both batch validation and as-you-type validation. The batch validation is "off" by default, until performance implications can be assessed.</p>
+<p>Added HTML validation, which validates against HTML spec 4.01 (with a few small variations), for both batch validation and as-you-type validation. The batch validation is "off" by default, until performance implications can be assessed.
+Note: a known limitation is this validation only works if the file extension (e.g. 'html') is in lowercase.</p>
<h3>API Changes from previous Build/Milestone</h3>
<h3>Problem reports fixed</h3>
