Add link to docs when using namecheap for email

src/views/email.html

@@ -519,6 +519,7 @@
                     </p>
                     <div id="collapse_dns_{{ record.value }}" class="panel-collapse collapse">
                       <div class="panel-body">
+                        <p ng-show="record.name === 'MX' && selectedDomain.provider === 'namecheap'"><a href="https://cloudron.io/documentation/domains/#namecheap-dns" target="_blank" class="btn btn-xs btn-danger">Namecheap and requires manual steps for MX records</a></p>
                         <p ng-show="expectedDnsRecords[record.value].name">Hostname: <b ng-click-select><tt>{{ expectedDnsRecords[record.value].name }}</tt></b></p>
                         <p ng-hide="expectedDnsRecords[record.value].name">Domain: <b ng-click-select><tt>{{ expectedDnsRecords[record.value].domain }}</tt></b></p>
                         <p>Record type: <b ng-click-select><tt>{{ expectedDnsRecords[record.value].type }}</tt></b></p>