Documentation/user-manual.txt: fix typo

Signed-off-by: Gustaf Hendeby <hendeby@isy.liu.se>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt
index 159de30..bee0d61 100644
--- a/Documentation/user-manual.txt
+++ b/Documentation/user-manual.txt
@@ -74,7 +74,7 @@
 
 Those snapshots aren't necessarily all arranged in a single line from
 oldest to newest; instead, work may simultaneously proceed along
-parallel lines of development, called <def_branch,branches>>, which may
+parallel lines of development, called <<def_branch,branches>>, which may
 merge and diverge.
 
 A single git repository can track development on multiple branches.  It