Fix cross reference

docs/usage/notes.rst

@@ -12,7 +12,7 @@ The chunker params influence how input files are cut into pieces (chunks)
 which are then considered for deduplication. They also have a big impact on
 resource usage (RAM and disk space) as the amount of resources needed is
 (also) determined by the total amount of chunks in the repository (see
-`Indexes / Caches memory usage` for details).
+:ref:`cache-memory-usage` for details).
 
 ``--chunker-params=10,23,16,4095`` results in a fine-grained deduplication|
 and creates a big amount of chunks and thus uses a lot of resources to manage