Add comment to gitignore

Change-Id: I6e77bc6dec1ba73cd13d7748672090b2e00d377f
diff --git a/.gitignore b/.gitignore
index 0efad7b..243b10d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
+# Ignore built artifacts
 site/
+
+# Ignore macOS files
 .DS_Store
\ No newline at end of file