Add detailed comments to .gitconfig explaining the fix

Clarifies why this configuration is needed to fix the Git 'dubious ownership'
issue that occurs in Podman container environments where the mount point
directory has different ownership than the files inside it.

Signed-off-by: Tiger Kaovilai <tkaovila@redhat.com>

Author: kaovilai

.gitconfig

@@ -1,2 +1,16 @@
+# Git configuration for containerized builds
+# 
+# This file fixes VCS stamping errors in Podman container environments.
+# When Docker/Podman mounts the repository, the mount point directory
+# (/github.com/vmware-tanzu/velero) is owned by root:root but the files
+# inside are owned by the mapped user. This ownership mismatch triggers
+# Git's "dubious ownership" security feature (introduced in Git 2.35.2+)
+# which causes git operations to fail with exit code 128.
+#
+# The safe.directory configuration tells Git to trust this specific
+# directory path, allowing VCS stamping and other git operations to
+# work properly in containerized builds.
+#
+# See: https://github.com/vmware-tanzu/velero/issues/9004
 [safe]
 	directory = /github.com/vmware-tanzu/velero