sync: link the internal-fs-layout doc into checkouts

This should make it easy to discover for people poking around .repo/.

Change-Id: Ie5051551f25127c0592df5e36efba7bb2263e5d4
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/323701
Reviewed-by: Jack Neus <jackneus@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 2e6afcc..1d778e1 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -1121,6 +1121,15 @@
 
 
 def _PostRepoUpgrade(manifest, quiet=False):
+  # Link the docs for the internal .repo/ layout for people
+  link = os.path.join(manifest.repodir, 'internal-fs-layout.md')
+  if not platform_utils.islink(link):
+    target = os.path.join('repo', 'docs', 'internal-fs-layout.md')
+    try:
+      platform_utils.symlink(target, link)
+    except:
+      pass
+
   wrapper = Wrapper()
   if wrapper.NeedSetupGnuPG():
     wrapper.SetupGnuPG(quiet)