Change header's relative link to /en/search/index.html (#72)

* Change header's relative link to /en/search/index.html

* Use https://docs.datastax.com/en/search/index.html in alg-search-form

Author: johnsmartco

gcx/styles/src/partials/header-content.hbs

@@ -36,7 +36,7 @@
           </div>
         </div>
         <div class="navbar-end__group">
-          <form id="alg-search-form" class="ds-search-form" action="../../search/index.html" target="_blank" method="GET">
+          <form id="alg-search-form" class="ds-search-form" action="https://docs.datastax.com/en/search/index.html" target="_blank" method="GET">
             <div>
               <div class="ds-search-input-icon">
                 <svg width="16" height="16" viewBox="0 0 14 14" fill="none" xmlns="http://www.w3.org/2000/svg">