docs: update tetragon logos in docs where necessary

docs/content/en/_index.html

@@ -23,7 +23,7 @@ <h1>
     </div>
 
     <div class="main-logo">
-      <img src="images/hero-illustration.png" alt="Tetragon logo illustration" width="100%">
+      <img src="svgs/hero-illustration.svg" alt="Tetragon logo illustration" width="100%">
     </div>
 
     <div class="users">
@@ -150,4 +150,4 @@ <h3>
       <a href="/docs/resources/" class="button video-button">See more videos</a>
     </div>
   </div>
-</div>
+</div>

docs/layouts/shortcodes/banner.html

@@ -10,5 +10,5 @@ <h2 class="banner__title">
     <a class="banner__link" href={{ .Get "link" }}>Getting started</a>
     {{ end }}
   </div>
-  <img class="banner__mascot" src="/images/jedi-bee-mascot.png" width="300" height="250" alt="Jedi bee" />
+  <img class="banner__mascot" src="/images/tetragon-shield.png" width="200" height="250" alt="Tetragon Shied" />
 </div>