[v9.4.x] Docs: Use correct function in labels and annotations docs (#65253)

Docs: Use correct function in labels and annotations docs (#65032)

Use correct function in labels and annotations docs

(cherry picked from commit 0464aebc8e)

Co-authored-by: Martin Beentjes <martinbeentjes@users.noreply.github.com>

docs/sources/alerting/fundamentals/annotation-label/variables-label-annotation.md

@@ -315,7 +315,7 @@ The `toUpper` function returns all text in uppercase.
 #### Example
 
 ```
-{{ toLower "Hello, world!" }}
+{{ toUpper "Hello, world!" }}
 ```
 
 ```