[doc] Add section content to empty implementation guidelines page

Signed-off-by: Marno van der Maas <mvdmaas+git@lowrisc.org>
diff --git a/doc/security/implementation_guidelines/_index.md b/doc/security/implementation_guidelines/_index.md
index 82708cc..ca03df7 100644
--- a/doc/security/implementation_guidelines/_index.md
+++ b/doc/security/implementation_guidelines/_index.md
@@ -1,3 +1,5 @@
 ---
 title: Implementation Guidelines
----
\ No newline at end of file
+---
+
+{{% sectionContent %}}