docs: fix code indentation (typeorm#8864)

bad indentation break syntax highlighting.

docs/select-query-builder.md

@@ -178,13 +178,13 @@ There are 5 different `QueryBuilder` types available:
 -   `RelationQueryBuilder` - used to build and execute relation-specific operations [TBD].
     Example:
 
-        ```typescript
-        await dataSource
-            .createQueryBuilder()
-            .relation(User,"photos")
-            .of(id)
-            .loadMany();
-        ```
+    ```typescript
+    await dataSource
+        .createQueryBuilder()
+        .relation(User,"photos")
+        .of(id)
+        .loadMany();
+    ```
 
 You can switch between different types of query builder within any of them,
 once you do, you will get a new instance of query builder (unlike all other methods).