Add missing anchor.

The "initial conditions" sections is referenced in the "test sharding" section,
so it needs an anchor.

PiperOrigin-RevId: 308031586
diff --git a/site/docs/test-encyclopedia.html b/site/docs/test-encyclopedia.html
index 4672f26..e2d1e06 100644
--- a/site/docs/test-encyclopedia.html
+++ b/site/docs/test-encyclopedia.html
@@ -190,7 +190,7 @@
 test runner may kill any stray processes.  Tests should not leak processes in
 this fashion.</p>
 
-<h2>Initial conditions</h2>
+<h2 id="initial-conditions">Initial conditions</h2>
 
 <p>When executing a test, the test runner must establish certain initial
 conditions.</p>