Clarify custom ranking rule usage (#3419)

---------

Co-authored-by: Many the fish <[email protected]>

Author: guimachiavelli

learn/relevancy/custom_ranking_rules.mdx

@@ -6,8 +6,6 @@ description: Custom ranking rules promote certain documents over other search re
 
 There are two types of ranking rules in Meilisearch: [built-in ranking rules](/learn/relevancy/ranking_rules) and custom ranking rules. This article describes the main aspects of using and configuring custom ranking rules.
 
-Custom ranking rules promote certain documents over other search results that are otherwise equally relevant.
-
 ## Ascending and descending sorting rules
 
 Meilisearch supports two types of custom rules: one for ascending sort and one for descending sort.
@@ -22,6 +20,14 @@ To add a custom ranking rule, you have to communicate the attribute name followe
 
 You can add this rule to the existing list of ranking rules using the [update settings endpoint](/reference/api/settings#update-settings) or [update ranking rules endpoint](/reference/api/settings#update-ranking-rules).
 
+## How to use custom ranking rules
+
+Custom ranking rules sort results in lexicographical order. For example, `Elena` will rank higher than `Ryu` and lower than `11` in a descending sort.
+
+Since this operation does not take into consideration document relevancy, in the majority of cases you should place custom ranking rules after the built-in ranking rules. This ensures that results are first sorted by relevancy, and the lexicographical sorting takes place only when two or more documents share the same ranking score.
+
+Setting a custom ranking rule at a high position may result in a degraded search experience, since users will see documents in alphanumerical order instead of sorted by relevance.
+
 ## Example
 
 Suppose you have a movie dataset. The documents contain the fields `release_date` with a timestamp as value, and `movie_ranking`, an integer that represents its ranking.

snippets/samples/code_samples_add_or_update_documents_1.mdx

@@ -82,15 +82,17 @@ await index.UpdateDocumentsAsync(movie);
 #[derive(Serialize, Deserialize)]
 struct IncompleteMovie {
   id: usize,
-  title: String
+  title: String,
+  genres: String
 }
 
 let task: TaskInfo = client
   .index("movies")
   .add_or_update(&[
     IncompleteMovie {
       id: 287947,
-      title: "Shazam ⚡️".to_string()
+      title: "Shazam ⚡️".to_string(),
+      genres: "comedy".to_string()
     }
   ], None)
   .await

snippets/samples/code_samples_typo_tolerance_guide_2.mdx

@@ -59,7 +59,6 @@ let typo_tolerance = TypoToleranceSettings {
   disable_on_words: None,
   min_word_size_for_typos: None,
 };
-
 let task: TaskInfo = client
   .index("movies")
   .set_typo_tolerance(&typo_tolerance)

snippets/samples/code_samples_typo_tolerance_guide_5.mdx

@@ -42,4 +42,18 @@ client.Index("movies").UpdateTypoTolerance(&meilisearch.TypoTolerance{
   DisableOnNumbers: true
 })
 ```
+
+```rust Rust
+// Deactivate typo tolerance on numbers and other high entropy words
+let typo_tolerance = TypoToleranceSettings {
+  disable_on_numbers: Some(true),
+  ..Default::default()
+};
+
+let task: TaskInfo = client
+  .index("movies")
+  .set_typo_tolerance(&typo_tolerance)
+  .await
+  .unwrap();
+```
 </CodeGroup>