Make weather icon URLs scheme-relative

changelog.html

@@ -39,11 +39,11 @@ Some tips:
 Help other Jenkins users by letting the community know which releases you've used,
 and whether they had any significant issues. <br>
 Legend: <br>
- <img src="http://ci.jenkins-ci.org/images/16x16/health-80plus.gif" width="16" height="16"
+ <img src="//ci.jenkins-ci.org/images/16x16/health-80plus.gif" width="16" height="16"
   alt="Sunny"> = I use it on my production site without major issues. <br>
- <img src="http://ci.jenkins-ci.org/images/16x16/health-40to59.gif" width="16" height="16"
+ <img src="//ci.jenkins-ci.org/images/16x16/health-40to59.gif" width="16" height="16"
   alt="Cloudy"> = I don't recommend it. <br>
- <img src="http://ci.jenkins-ci.org/images/16x16/health-00to19.gif" width="16" height="16"
+ <img src="//ci.jenkins-ci.org/images/16x16/health-00to19.gif" width="16" height="16"
   alt="Lightning"> = I tried it but rolled back to a previous version. <br>
 View ratings below, and click one of the icons next to your version to provide your input.
 </div>