Documentation: credit Fyra Stack for hosting the demo

docs/assets/sponsors/fyra-stack.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="666.667" height="666.667" viewBox="0 0 666.667 666.667"><g stroke-width="1.333"><path fill="#fef400" d="m332.66668 418.66668h-84.66667v-85.33334-85.33333h84.66667 84.66667v-85.33334-85.333334h85.33333 85.33334v85.333334 85.33334h-85.33334-85.33333v85.33333 85.33334z"/><path fill="#fe6565" d="m248.00001 589.33335h-170.666674v-170.66667-170.66667h85.333334 85.33334v-85.33334-85.333334h84.66667 84.66667v85.333334 85.33334h85.33333 85.33334v85.33333 85.33334h-84.66667-84.66667v85.33334 85.33333zm84.66667-170.66667h84.66667v-85.33334-85.33333h-84.66667-84.66667v85.33333 85.33334z"/></g></svg>

docs/index.md

@@ -13,9 +13,8 @@ physical documents into a searchable online archive so you can keep, well, _less
 [Demo](https://demo.paperless-ngx.com){ .md-button .md-button--secondary target=\_blank }
 
 <div style="display: flex; justify-content: end; margin-top: -1.5rem;">
-  <a href="https://m.do.co/c/8d70b916d462" target="_blank">
-    <img src="https://opensource.nyc3.cdn.digitaloceanspaces.com/attribution/assets/PoweredByDO/DO_Powered_by_Badge_white.svg#only-dark" class="no-lightbox" width="150px">
-    <img src="https://opensource.nyc3.cdn.digitaloceanspaces.com/attribution/assets/PoweredByDO/DO_Powered_by_Badge_black.svg#only-light" class="no-lightbox" width="150px">
+  <a href="https://fyrastack.com" target="_blank" aria-label="Demo hosting provided by Fyra Stack">
+    <img src="assets/sponsors/fyra-stack.svg" alt="" class="no-lightbox" width="28px" style="vertical-align: middle;"> Fyra Stack
   </a>
 </div>