Split paragraph into two

There was an awkward line break in this text, and the line length was
too long because there was no grid on the page.

Splitting it into two paragraphs makes it:
- read nicer
- avoids any awkward line breaks

app/templates/views/api/keys/show.html

@@ -14,8 +14,10 @@
     </h1>
 
     <p>
-      Copy your key to somewhere safe. You won’t be able to see it again
-      once you leave this page.
+      Copy your key to somewhere safe.
+    </p>
+    <p>
+      You won’t be able to see it again once you leave this page.
     </p>
 
     <div class="bottom-gutter-2">