Dsm 309 introduction to secure by design (#191)

* DSM-309 Added intro to Secure by Design

* DSM-309 minor edits

As agreed with John S.

* Fix typo

src/secure-by-design/index.njk

@@ -79,7 +79,7 @@
         <ul class="govuk-list govuk-list--bullet">
             <li>consider cyber security from the start</li>
             <li>choose appropriate security frameworks and controls</li>
-            <li>continuously managing risks</li>
+            <li>continuously manage risks</li>
         </ul>
 
 {{ component('inset-text', {
@@ -113,7 +113,6 @@
 
         <p class="govuk-body">To access the Secure by Design portal, you must work in Defence or for one of our suppliers. If you do not have access, ask a senior military or MOD civil servant on your team to arrange it for you.</p>
 
-
         <h3 class="govuk-heading-m">Related guidance</h3>  
 
       <ul class="govuk-list">