Add multi-manifest support with <submanifest> elementv2.22

To be addressed in another change:
 - a partial `repo sync` (with a list of projects/paths to sync)
   requires `--this-tree-only`.

Change-Id: I6c7400bf001540e9d7694fa70934f8f204cb5f57
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/322657
Tested-by: LaMont Jones <lamontjones@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/docs/internal-fs-layout.md b/docs/internal-fs-layout.md
index 0e830510..a9bd1d26 100644
--- a/docs/internal-fs-layout.md
+++ b/docs/internal-fs-layout.md
@@ -50,6 +50,10 @@ For example, if you want to change the manifest branch, you can simply run
 For more documentation on the manifest format, including the local_manifests
 support, see the [manifest-format.md] file.
 
+*   `submanifests/{submanifest.path}/`: The path prefix to the manifest state of
+    a submanifest included in a multi-manifest checkout.  The outermost manifest
+    manifest state is found adjacent to `submanifests/`.
+
 *   `manifests/`: A git checkout of the manifest project.  Its `.git/` state
     points to the `manifest.git` bare checkout (see below).  It tracks the git
     branch specified at `repo init` time via `--manifest-branch`.