Update TOC (shader-slang#2764)

Co-authored-by: Yong He <yhe@nvidia.com>

Author: csyonghe

docs/user-guide/toc.html

@@ -105,6 +105,7 @@
 <li data-link="a1-02-slangpy"><span>Using Slang to Write PyTorch Kernels</span>
 <ul class="toc_list">
 <li data-link="a1-02-slangpy#getting-started-with-slangpy"><span>Getting Started with slangpy</span></li>
+<li data-link="a1-02-slangpy#back-propagating-derivatives-through-complex-access-patterns"><span>Back-propagating Derivatives through Complex Access Patterns</span></li>
 <li data-link="a1-02-slangpy#builtin-library-support-for-pytorch-interop"><span>Builtin Library Support for PyTorch Interop</span></li>
 <li data-link="a1-02-slangpy#type-marshalling-between-slang-and-python"><span>Type Marshalling Between Slang and Python</span></li>
 </ul>