Doc: update @knownissues for \grace and \tempo inside \times{}

As Dmytro suggested, the description could be clearer.
Hopefully it is now!

diff --git a/Documentation/notation/rhythms.itely b/Documentation/notation/rhythms.itely
index e1d7476d837b829177a6088b55e8398db16e7520..d1e92ac2c6ba43f7de203472e1594702fc0514aa 100644 (file)
--- a/Documentation/notation/rhythms.itely
+++ b/Documentation/notation/rhythms.itely
@@ -290,12 +290,16 @@ Internals Reference:
 @cindex grace notes within tuplet brackets
 
 @knownissues
-When the first note on a staff is a grace note followed by a
-tuplet the grace note must be placed before the @code{\times}
-command to avoid errors.  Anywhere else, grace notes may be
-placed within tuplet brackets.  When using a tuplet at the beginning
-of a piece with a @code{\tempo} mark, you must add an explicit
-@code{\new Voice} as discussed in @rlearning{Voices contain music}.
+Grace notes may be placed within tuplet brackets, @emph{except}
+when a staff begins with a grace note followed by a tuplet.  In this
+particular case, the grace note must be placed before the @code{\times}
+command to avoid errors.
+
+@cindex tempo marks within tuplet brackets
+
+When using a tuplet at the beginning of a piece with a @code{\tempo}
+mark, the music must be explicitely entered in a @code{\new Voice}
+block, as discussed in @rlearning{Voices contain music}.
 
 
 @node Scaling durations