Fix image on Containers page for light/dark mode.

Author: insectengine

_includes/container-first.html

@@ -3,12 +3,13 @@
 <div class="full-width-bg component">
   <div class="grid-wrapper">
     <div class="width-3-12 width-12-12-m">
-    <img class="light-only" src="{{site.baseurl}}/assets/images/about/icon-containerfirst.svg">
-    <img class="dark-only" src="{{site.baseurl}}/assets/images/about/icon-containerfirst-dark.svg">
+    <img class="light-only" src="{{site.baseurl}}/assets/images/about/icon-containerfirst.svg" alt="Container image">
+    <img class="dark-only" src="{{site.baseurl}}/assets/images/about/icon-containerfirst-dark.svg" alt="Container image">
     </div>
     <div class="width-9-12 width-12-12-m">
       <p class="intropara">From the outset, Quarkus has been designed around a container-first philosophy. What this means in concrete terms is that Quarkus applications are optimised for low memory usage and fast startup times in the following ways:</p>
-      <img src="../guides/images/build-time-principle.png" alt="Quarkus Build Time Principle" width="90%">
+      <img class="light-only" src="{{site.baseurl}}/assets/images/container/build-time-principle-light.png" alt="Quarkus Build Time Principle" width="90%">
+      <img class="dark-only" src="../guides/images/build-time-principle.png" alt="Quarkus Build Time Principle" width="90%">
     </div>
     <div class="width-12-12 width-12-12-m">
         <h2>Build Time Processing</h2>