Update garbage-collection.md

Author: open-documents

content/manuals/build/cache/garbage-collection.md

@@ -47,8 +47,8 @@ you have 11GB worth of build cache, where:
 - 7GB of which is "stale" cache
 - 4GB is other, more valuable cache
 
-A GC sweep would delete 5GB of stale cache as part of the 1st policy, with a
-remainder of 6GB, meaning the 2nd policy does not need to clear any more cache.
+A GC sweep would delete 2GB of stale cache as part of the 1st policy, with a
+remainder of 9GB, meaning the 2nd policy does not need to clear any more cache.
 
 The default GC policies are (approximately):