Fix spelling

Author: rly

_includes/header.html

@@ -14,7 +14,7 @@
       <ul class="nav navbar-nav navbar-right">
         <li><a href="{{ site.url }}{{ site.baseurl }}/">Home</a></li>
          <li class="dropdown">
-            <a class="dropdown-toggle" data-toggle="dropdown" href="#">Software Respositories<span class="caret"></span></a>
+            <a class="dropdown-toggle" data-toggle="dropdown" href="#">Software Repositories<span class="caret"></span></a>
                <ul class="dropdown-menu">
                  <li class="dropdown-header"><b>NWB APIs</b></li>
                  <li><a href="https://github.com/NeurodataWithoutBorders/pynwb">PyNWB</a></li>