security: cleanup validation error reporting

Change-Id: I313bedb336ecfb4180ba0f31ad77666544ba1c10
diff --git a/docs/INSTALL.rst b/docs/INSTALL.rst
index 45652ab..f9492db 100644
--- a/docs/INSTALL.rst
+++ b/docs/INSTALL.rst
@@ -42,7 +42,7 @@
 To build ndn-cxx from source, one must first install a C++ compiler and all necessary
 development tools and libraries:
 
-- On **Ubuntu**
+- On **Debian** and **Ubuntu**
 
     In a terminal, enter::
 
@@ -98,7 +98,7 @@
 
       export PATH="${HOME}/.local/bin${PATH:+:}${PATH}"
 
-- On **Ubuntu**:
+- On **Debian** and **Ubuntu**:
 
   .. code-block:: sh