Make "users" possessive where appropriate

Author: tylerhunt

src/templates/docs/font-family/index.html

@@ -35,7 +35,7 @@ <h3 class="f6 ttu tracked mt0">Font Family</h3>
         </p>
         <p class="measure f5 f4-ns lh-copy">
           Relying on systems fonts greatly improves page performance and can also help
-          your web application/site blend in with the users operating
+          your web application/site blend in with the user's operating
           system. Readability is strongly linked to familiarity, so
           this helps create a more fluid reading experience, allowing your users to
           focus on your content.

src/templates/index.html

@@ -133,7 +133,7 @@ <h1 class="f5 ttu tracked fw6">Principles</h1>
                   <article class="fl pv2 w-100 w-third-l pr4-l">
                     <h2 class="f5 f4-ns fw6 mb0">Responsive</h2>
                     <p class="f6 f5-ns measure lh-copy mt0">
-                      Everything should be 100% responsive. Your website should work regardless of a users
+                      Everything should be 100% responsive. Your website should work regardless of a user's
                       device or screensize.
                     </p>
                   </article>