Add k3sign repo link

Author: Grippy98

index.html

@@ -120,6 +120,14 @@ <h3>Key Configuration Tool</h3>
                             BMPKH, key counts, software revisions, and more.</p>
                         <span class="tool-link-arrow">View Tool →</span>
                     </a>
+
+                    <a href="https://github.com/TexasInstruments/k3sign" target="_blank" rel="noopener noreferrer"
+                        class="tool-card">
+                        <h3>k3sign Security Tool</h3>
+                        <p>Command line tool for signing and encrypting images for TI K3 devices. Supports x509
+                            certificates and secure boot workflows.</p>
+                        <span class="tool-link-arrow">Visit Repo →</span>
+                    </a>
                 </div>
             </section>