Doc: LM Tweaking output: Fix 1180

Doc: LM Tweaking output: Fix 1180

 - The "real music" example overrides the line-width in the call
   to lilypond, but the overriden length is too small, resulting
   in an unwanted line break.  Note that if the line-width is not
   overridden the break occurs at the end of measure 2, resulting
   in a collision of the phrasing slur with the 6/4 time signature.

   This example should be reconsidered as part of issue 1015.