Update heading

Author: CaroFG

learn/indexing/optimize_indexing_performance.mdx

@@ -46,7 +46,7 @@ Focus on the **longest-running steps** and investigate which index settings or d
 |--------------|--------------|
 | Tokenizes text and builds the inverted index. | Ensure the [searchable attributes](/reference/api/settings#searchable-attributes) list only includes the fields you want to be checked for query word matches. |
 
-### `extracting word proximity`, `merging word proximity`
+### `extracting word proximity` and `merging word proximity`
 
 | Description | Optimization |
 |--------------|--------------|