docs: add actions-ref limitation comment to reusable workflows

Explain why actions-ref input must match the caller's @ref — GitHub
Actions does not expose the called ref to reusable workflows, and
relative paths (./) resolve to the caller's repo context.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Hua-Wei Chen <huaweic@nvidia.com>

Author: huaweic-nv

.github/workflows/dsx-ci-go.yml

@@ -13,8 +13,17 @@
 # limitations under the License.
 
 # Reusable CI workflow for DSX Go projects.
-# Each job checks out the caller's repo + dsx-github-actions at the same
-# ref used by the caller, so pinning the workflow ref pins all actions.
+#
+# IMPORTANT: actions-ref must match the ref used to call this workflow.
+# GitHub Actions does not provide a way for reusable workflows to know
+# which ref they were called with -- uses: requires a static string and
+# relative paths (./) resolve to the caller's repo, not this one.
+# This is a known GitHub Actions platform limitation.
+#
+# Example:
+#   uses: NVIDIA/dsx-github-actions/.github/workflows/dsx-ci-go.yml@v1.15.0
+#   with:
+#     actions-ref: v1.15.0  # must match the @ref above
 
 name: DSX Go CI
 

.github/workflows/dsx-ci-helm.yml

@@ -13,6 +13,17 @@
 # limitations under the License.
 
 # Reusable CI workflow for DSX Helm chart projects.
+#
+# IMPORTANT: actions-ref must match the ref used to call this workflow.
+# GitHub Actions does not provide a way for reusable workflows to know
+# which ref they were called with -- uses: requires a static string and
+# relative paths (./) resolve to the caller's repo, not this one.
+# This is a known GitHub Actions platform limitation.
+#
+# Example:
+#   uses: NVIDIA/dsx-github-actions/.github/workflows/dsx-ci-helm.yml@v1.15.0
+#   with:
+#     actions-ref: v1.15.0  # must match the @ref above
 
 name: DSX Helm CI