Note default cache directory root on macOS
On Darwin systems it looks like the cache is written to this location.
Closes #10579.
PiperOrigin-RevId: 295144923
diff --git a/site/docs/output_directories.md b/site/docs/output_directories.md
index b007bf3..068a9b7 100644
--- a/site/docs/output_directories.md
+++ b/site/docs/output_directories.md
@@ -26,9 +26,12 @@
* Bazel must be invoked from a directory containing a WORKSPACE file. It reports
an error if it is not. We call this the _workspace directory_.
-* The _outputRoot_ directory is ~/.cache/bazel. (Unless `$TEST_TMPDIR` is
- set, as in a test of bazel itself, in which case this directory is used
- instead.)
+* The _outputRoot_ directory defaults to `~/.cache/bazel` on Linux,
+ `/private/var/tmp` on macOS, and on Windows it defaults to `%HOME%` if set,
+ else `%USERPROFILE%` if set, else the result of calling
+ `SHGetKnownFolderPath()` with the `FOLDERID_Profile` flag set. If the
+ environment variable `$TEST_TMPDIR` is set, as in a test of bazel itself,
+ then that value overrides the default.
* We stick the Bazel user's build state beneath `outputRoot/_bazel_$USER`. This
is called the _outputUserRoot_ directory.
* Beneath the `outputUserRoot` directory, we create an `installBase` directory
