st.1: add an entry for ISO-14755 shortcut

st.1

@@ -162,6 +162,10 @@ Copy the selected text to the clipboard selection.
 .TP
 .B Alt-Shift-v
 Paste from the clipboard selection.
+.TP
+.B Alt-Ctrl
+Launch dmenu to enter a unicode codepoint and send the corresponding glyph
+to st.
 .SH CUSTOMIZATION
 .B st
 can be customized by creating a custom config.h and (re)compiling the source