docs: add b4 trailers documentation

Completes the "ez" set of features added in 0.10.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

1 files changed, 36 insertions, 1 deletions

diff --git a/docs/contributor/trailers.rst b/docs/contributor/trailers.rst
index 2984030..fb88c0d 100644
--- a/docs/contributor/trailers.rst
+++ b/docs/contributor/trailers.rst
@@ -1,4 +1,39 @@
 trailers: retrieving code-review trailers
 =========================================
+This commands allows you to easily retrieve code-review trailers sent in
+reply to your work and apply them to the matching commits. It will
+retrieve code-review trailers sent in response to any previously
+submitted versions of your series, as long as:
 
-Stub.
+* either the patch-id of the commit still matches what was sent, or
+* the title of the commit is exactly the same
+
+You can always edit the trailers after they are applied by using ``git
+rebase -i`` and choosing ``reword`` as action.
+
+Most commonly, you just need to run::
+
+    b4 trailers -u
+
+Command flags
+-------------
+``-u, --update``
+  Update branch commits with latest received trailers.
+
+``-S, --sloppy-trailers``
+  Accept trailers where the email address of the sender differs from the
+  email address found in the trailer itself.
+
+``-F MSGID, --trailers-from MSGID``
+  Look for trailer updates in an arbitrary tread found on the
+  public-inbox server. Note, that this is generally only useful in the
+  following two cases:
+
+  * for branches not already managed by ``b4 prep``
+  * when a single larger series is broken up into multiple smaller
+    series (or vice-versa)
+
+``--since SINCE``
+  Only useful with ``-F``. By default, b4 will only look for your own
+  commits as far as 1 month ago. With this flag, you can instruct it to
+  look further back.