Add cross reference for package_cache_during_build in docs (#1598)

Signed-off-by: brycegbrazen <bryce.gattis@brazenanimation.com>

docs/source/managing_packages.rst

@@ -222,6 +222,12 @@ the cache is to copy that content locally instead, and avoid the network cost.
    Please note: Package caching does **NOT** cache package
    definitions. Only their payloads (ie, the package root directory).
 
+Build behavior
+--------------
+
+Package caching during a package build is disabled by default. To enable caching during
+a package build, you can set :data:`package_cache_during_build` to True.
+
 .. _enabling-package-caching:
 
 Enabling Package Caching