Fix file comment on call_hierarchy

Signed-off-by: Danila Fedorin <daniel.fedorin@hpe.com>

tools/chpl-language-server/test/call_hierarchy.py

@@ -1,6 +1,5 @@
 """
-Tests basic functionality, including autocompletion, go-to-definition, hover,
-and references
+Test the call hierarchy feature, which computes calls between functions.
 """
 
 import sys