message: Display pre-release status in new releases emails
  Closes
diff: @@ -117,6 +117,22 @@ var newReleaseEmailTmpl = template.Must(template.New("").Parse(`
  </td>
  </tr>
  + <tr>
  + <td>
  + {{ if .Package.prerelease }}
  + <table border="0" cellpadding="0" cellspacing="0" style="border-collapse: separate; mso-table-lspace: 0pt; mso-table-rspace: 0pt; width: 100%; box-sizing: border-box;">
  + <tbody>
  + <tr>
  + <td class="content-block powered-by" style="font-family: sans-serif; vertical-align: top; padding-top: 5px; padding-bottom: 30px;">
  + <div style="color: #ffffff; color: #856404; background-color: #fff3cd; border: 1px solid #ffeeba; border-radius: 5px; box-sizing: border-box; cursor: pointer; font-size: 14px; font-weight: 400; margin: 0; padding: 12px 25px; text-align: left;">This package version is a <b>pre-release</b> and it is not ready for production use.</div>
  + </td>
  + </tr>
  + </tbody>
  + </table>
  + {{ end }}
  + </td>
  + </tr>
  +
  <tr>
  <td style="font-family: sans-serif; font-size: 14px;">
  {{ if .Package.changes }}
  