doc: add info about new hardstatus escape %e

src/doc/screen.1

@@ -4058,6 +4058,8 @@ Here is the full list of supported escapes:
 the escape character itself
 .IP E
 sets %? to true if the escape character has been pressed.
+.IP e
+encoding
 .IP f
 flags of the window, see \*Qwindows\*U for meanings of the various flags
 .IP F

src/doc/screen.texinfo

@@ -5571,6 +5571,8 @@ day number
 weekday name
 @item E
 sets %? to true if the escape character has been pressed.
+@item e
+encoding
 @item f
 flags of the window. @xref{Windows}, for meanings of the various flags.
 @item F