espie@ added feature

Index: docs/man/mupdf.1
--- docs/man/mupdf.1.orig
+++ docs/man/mupdf.1
@@ -94,6 +94,9 @@ Pan page left or right.
 .TP
 .B Control + Scroll wheel
 Zoom in or out.
+.TP
+.B Shift + Control + Scroll wheel
+Fine grained Zoom in or out.
 
 .SH KEY BINDINGS