[PATCH v2 2/2] checkpatch: document new check PLACEHOLDER_USE

["Onur Özkan" <work@onurozkan.dev>]

Adds documentation for the new check PLACEHOLDER_USE
in checkpatch.

Signed-off-by: Onur Özkan <work@onurozkan.dev>
---
 Documentation/dev-tools/checkpatch.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index d5c47e560324..4dccd1036870 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -1245,6 +1245,16 @@ Others
     The patch file does not appear to be in unified-diff format.  Please
     regenerate the patch file before sending it to the maintainer.
 
+  **PLACEHOLDER_USE**
+    Detects unhandled placeholder text left in cover letters or commit headers/logs.
+    Common placeholders include lines like::
+
+      *** SUBJECT HERE ***
+      *** BLURB HERE ***
+
+    These typically come from autogenerated templates. Replace them with a proper
+    subject and description before sending.
+
   **PRINTF_0XDECIMAL**
     Prefixing 0x with decimal output is defective and should be corrected.
 
-- 
2.51.0