fix(includes): replace nav role "nav" with "navigation"

Author: remarkablemark

_includes/nav.html

@@ -1,6 +1,6 @@
 <input type="checkbox" id="nav-toggle">
 
-<nav role="nav" class="nav noselect">
+<nav role="navigation" class="nav noselect">
   <ul class="nav-list">
     <li>
       <label id="nav-close" aria-label="Hide navigation" for="nav-toggle" role="button" tabindex="0" onkeypress="rmk.toggleNav(event)">&#x2715;</label>