[rhythmbox] help: Make all keyboard shortcuts capital letters

[Andre Klapper <aklapper src gnome org>]

commit 4d16d9bf83da9db0cb2f1ede31767307fe33bf65
Author: Andre Klapper <a9016009 gmx de>
Date:   Wed Jan 1 22:37:09 2020 +0100

    help: Make all keyboard shortcuts capital letters

 help/C/index.docbook | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/help/C/index.docbook b/help/C/index.docbook
index 449ab0933..fdefb6bef 100644
--- a/help/C/index.docbook
+++ b/help/C/index.docbook
@@ -1335,7 +1335,7 @@
               <entry>
                 <keycombo>
                   <keycap>Ctrl</keycap>
-                  <keycap>p</keycap>
+                  <keycap>P</keycap>
                 </keycombo>
               </entry>
               <entry>