Add some aria roles to search form and search alert

Author: oalders

root/home.tx

@@ -33,7 +33,7 @@
       <img src="/static/images/metacpan-logo.svg" alt="MetaCPAN" />
     </div>
     <h4>A search engine for <a href="https://www.cpan.org">CPAN</a></h4>
-    <form action="/search" class="search-form form-horizontal">
+    <form action="/search" class="search-form form-horizontal" role="search">
       <input type="hidden" name="size" id="metacpan_search-size" value="20">
       <div class="form-group">
           <div class="search-group">

root/no_result.tx

@@ -5,8 +5,8 @@
 <div class="no-results">
     <h3 class="search-results-header">No search results for [% $search_query %]</h3>
     %%  if $suggest {
-            <div class="alert alert-danger">
-                Did you mean :
+            <div class="alert alert-danger" role="alert">
+                Did you mean:
                 <a href="/search?q=[% $suggest | uri %]">[% $suggest %]</a>
             </div>
     %%  }