Add instructions on importing signing key using command line

wiki/src/install/inc/steps/download.inline.html

@@ -423,10 +423,23 @@ importing keys|https://gpgtools.tenderapp.com/kb/gpg-keychain-faq/how-to-find-pu
 
 <h3>Using the command line</h3>
 
+
 <ol>
 
   <li>
-   Open a terminal and navigate to the folder where you saved the
+    <p>Download the [[Tails signing key|tails-signing.key]] and import it into
+    <span class="application">GnuPGP</span>.</p>
+
+    <p>To import the Tails signing key into
+    <span class="application">GnuPGP</span>, open a terminal and navigate to
+    the folder where you saved the Tails signing key.</p>
+
+    <p>Execute:</p>
+
+    <p class="pre">gpg --import tails-signing.key</p>
+  </li>
+  <li>
+   In a terminal, navigate to the folder where you saved the
    image and the signature.
   </li>