add logo to footer

see #3
The order are changed to make the looking more balanced. This order might be changed in the future.

layouts/partials/docs/inject/footer.html

@@ -1,17 +1,22 @@
 <div id="sponsors" class="flex flex-wrap justify-between" style="max-height: 150px;">
     <span>
       <picture>
-          <source srcset='{{ "images/logo01-erc-dark.png" | relURL }}' media="(prefers-color-scheme: dark)">
-          <img src='{{ "images/logo01-erc.jpg" | relURL }}' style="height: auto; width: 27%;" />
+            <source srcset='/translations/images/logo04-heidelberg-cats.png' media="(prefers-color-scheme: light)">
+            <source srcset='/translations/images/logo04-heidelberg-cats-dark.png' media="(prefers-color-scheme: dark)">
+            <img src='translations/images/logo04-heidelberg-cats.png' style="height: auto; width: 28%;" />
       </picture>
       <picture>
           <source srcset='{{ "images/logo03-uni-dark.png" | relURL }}' media="(prefers-color-scheme: dark)">
-          <img src='{{ "images/logo03-uni.png" | relURL }}' style="height: auto; width: 27%;" />
+          <img src='{{ "images/logo03-uni.png" | relURL }}' style="height: auto; width: 18%;" />
+      </picture>
+      <picture>
+          <source srcset='{{ "images/logo01-erc-dark.png" | relURL }}' media="(prefers-color-scheme: dark)">
+          <img src='{{ "images/logo01-erc.jpg" | relURL }}' style="height: auto; width: 18%;" />
       </picture>
         <picture>
             <source srcset='{{ "images/logo02-readc-light.png" | relURL }}' media="(prefers-color-scheme: light)">
             <source srcset='{{ "images/logo02-readc.png" | relURL }}' media="(prefers-color-scheme: dark)">
-            <img src='{{ "images/logo02-readc.png" | relURL }}' style="height: auto; width: 35%;" />
+            <img src='{{ "images/logo02-readc.png" | relURL }}' style="height: auto; width: 27%;" />
         </picture>
     </span>
 </div>