Adds bar line section to LM (Issue 3408) (issue 12724043)

[PhilEHolmes]

Reviewers: Trevor Daniels,

Message:
Please review.

Description:
Adds bar line section to LM (Issue 3408)

Please review this at https://codereview.appspot.com/12724043/

Affected files:
  M Documentation/learning/common-notation.itely


Index: Documentation/learning/common-notation.itely
diff --git a/Documentation/learning/common-notation.itely  
b/Documentation/learning/common-notation.itely
index  
55f91d66734d83c07e88ce59a3633cb05c161c78..4e5753f24f3275c5cf072b2af4031b0a339d489c  
100644
--- a/Documentation/learning/common-notation.itely
+++ b/Documentation/learning/common-notation.itely
@@ -51,7 +51,7 @@ This section introduces common notation that is used for  
one voice
 on one staff.

 @menu
-* Bar checks::
+* Bar lines and bar checks::
 * Accidentals and key signatures::
 * Ties and slurs::
 * Articulation and dynamics::
@@ -61,8 +61,23 @@ on one staff.
 @end menu


address@hidden Bar checks
address@hidden Bar checks
address@hidden Bar lines and bar checks
address@hidden Bar lines and bar checks
+
address@hidden Bar lines
+
+Single bar lines are automatically placed in the music so
+there is no need to add them manually.  Other types of bar
+lines are added using @code{\bar}, for example
address@hidden "||"} for a double bar line, or @code{\bar "|."}
+for an ending bar line.  For a full list of bar lines see
+the @ruser{Bar lines}.
+
address@hidden,quote,relative=2]
+g1 e1 \bar "||" c2. c'4 \bar "|."
address@hidden lilypond
+
address@hidden Bar checks

 Though not strictly necessary, @emph{bar checks} should be
 used in the input code to show where bar lines are expected