Docs: replace deprecated GHIcons logo with Primer Octovisuals asset

GHIcons is deprecated and the hot-linked URL now 404s. The replacement
`code-ql` icon is hosted alongside the site's other assets, so the
`../` path matches the nav links already in this file.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: redsun82

docs/codeql/index.html

@@ -66,7 +66,7 @@
     </div>
     <article class="pb-6" style="min-height: calc(100vh - 68px);">
         <div class="blankslate">
-            <img src="https://ghicons.github.com/assets/images/blue/svg/Code%20QL.svg" class="mb-3" />
+            <img src="../assets/img/svgs/codeql.svg" alt="" class="mb-3" />
             <h1>CodeQL documentation</h1>
             <p class="f2">CodeQL enables you to query code as though it were data. Write a query to find all variants of a
                 vulnerability, eradicating it forever. Then share your query to help others do the same.</p>