[PATCH v2 1/6] Documentation/git-diff-tree.txt: fix formatting

["SZEDER Gábor" <szeder.dev@gmail.com>]

Asciidoctor versions v1.5.7 or later print the following warning while
building the documentation:

      ASCIIDOC git-diff-tree.xml
  asciidoctor: WARNING: diff-format.txt: line 2: unterminated listing block

This highlights an issue (even with older Asciidoctor versions) where
the "Raw output format" header is not rendered as a header, and the
rest of the document is rendered in monospace.  This is not caused by
'diff-format.txt' in itself, but rather by 'git-diff-tree.txt'
including 'pretty-formats.txt' and 'diff-format.txt' on subsequent
lines, while the former happens to end with monospace-formatted
example commands.

Fix this by inserting an empty line between the two include::
directives.

The page rendered with AsciiDoc doesn't have this formatting issue.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---
 Documentation/git-diff-tree.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/git-diff-tree.txt b/Documentation/git-diff-tree.txt
index 24f32e8c54..5c8a2a5e97 100644
--- a/Documentation/git-diff-tree.txt
+++ b/Documentation/git-diff-tree.txt
@@ -118,6 +118,7 @@ include::pretty-options.txt[]
 
 
 include::pretty-formats.txt[]
+
 include::diff-format.txt[]
 
 GIT
-- 
2.21.0.539.g07239c3a71.dirty