Add anchor for "Heterogeneous Lookup in Associative Containers" section

Author: Rageking8

docs/standard-library/stl-containers.md

@@ -39,7 +39,7 @@ Both `map` and `set` only allow one instance of a key or element to be inserted
 
 Ordered maps and sets support bi-directional iterators, and their unordered counterparts support forward iterators. For more information, see [Iterators](../standard-library/iterators.md).
 
-### Heterogeneous Lookup in Associative Containers (C++14)
+### <a name="heterogeneous-lookup-in-associative-containers"></a> Heterogeneous Lookup in Associative Containers (C++14)
 
 The ordered associative containers (map, multimap, set, and multiset) now support heterogeneous lookup, which means that you're no longer required to pass the exact same object type as the key or element in member functions such as `find()` and `lower_bound()`. Instead, you can pass any type for which an overloaded `operator<` is defined that enables comparison to the key type.