Merge branch 'jt/trailer-with-cruft'

Doc update.

* jt/trailer-with-cruft:
  doc: mention user-configured trailers

Documentation/git-interpret-trailers.txt

@@ -49,7 +49,8 @@ will be added before the new trailer.
 
 Existing trailers are extracted from the input message by looking for
 a group of one or more lines that (i) are all trailers, or (ii) contains at
-least one Git-generated trailer and consists of at least 25% trailers.
+least one Git-generated or user-configured trailer and consists of at
+least 25% trailers.
 The group must be preceded by one or more empty (or whitespace-only) lines.
 The group must either be at the end of the message or be the last
 non-whitespace lines before a line that starts with '---'. Such three