Add tuning

common.ly

@@ -5,6 +5,12 @@ common = {
   \time 2/4
 }
 
+guitarTuning = \mark \markup \column {
+  \line {
+    \override #'(font-size . 0.05) { \circle 6 }
+    \small "= D2"
+  }
+}
 copyright = \markup \center-column {
   \smaller {
     \concat {

music/1-introduction/guitar.ly

@@ -3,6 +3,7 @@
 guitarVoiceOne = \relative c' {
 
   % 01
+  \guitarTuning
   \mark \markup \normalsize "Andante"
   <f a,>4\p q8 \grace g16 q8. <e g,>16 <d f,>8 |
   cis4 <cis bes g>8\f q4 r8 |