Add a security & privacy considerations section to the explainer temp…

…late.

README.md

@@ -43,6 +43,7 @@ reference. Look for [brackets].
 - [Considered alternatives](#considered-alternatives)
   - [[Alternative 1]](#alternative-1)
   - [[Alternative 2]](#alternative-2)
+- [Security and Privacy Considerations](#security-and-privacy-considerations)
 - [Stakeholder Feedback / Opposition](#stakeholder-feedback--opposition)
 - [References & acknowledgements](#references--acknowledgements)
 
@@ -154,6 +155,13 @@ and why you decided against it.]
 
 [etc.]
 
+## Security and Privacy Considerations
+
+[This section can start out as your answers to the [Security and Privacy Self-Review
+Questionnaire](https://www.w3.org/TR/security-privacy-questionnaire/), but you should eventually
+focus it on the aspects of your feature that need special security or privacy attention from
+implementers or users.]
+
 ## Stakeholder Feedback / Opposition
 
 [Implementors and other stakeholders may already have publicly stated positions on this work. If you can, list them here with links to evidence as appropriate.]