try manually updating toc

Author: MaryaBelanger

src/content/effective-dart/_toc.md

@@ -105,7 +105,7 @@ $ dart run dart_site effective-dart
 * <a href='/effective-dart/usage#dont-use-an-explicit-default-value-of-null'>DON'T use an explicit default value of <code>null</code>.</a>
 * <a href='/effective-dart/usage#dont-use-true-or-false-in-equality-operations'>DON'T use <code>true</code> or <code>false</code> in equality operations.</a>
 * <a href='/effective-dart/usage#avoid-late-variables-if-you-need-to-check-whether-they-are-initialized'>AVOID <code>late</code> variables if you need to check whether they are initialized.</a>
-* <a href='/effective-dart/usage#consider-assigning-a-nullable-field-to-a-local-variable-to-enable-type-promotion'>CONSIDER assigning a nullable field to a local variable to enable type promotion.</a>
+* <a href='/effective-dart/usage#consider-work-arounds-to-enable-type-promotion-for-nullable-fields'>CONSIDER assigning a nullable field to a local variable to enable type promotion.</a>
 
 **Strings**