Remove generated manual dash.info

Both GNU ELPA and MELPA are able to and do generate .info manuals
from corresponding .texi files.  This means that we no longer need
to maintain dash.info, which is a hassle.

* create-docs.sh: Run under Bourne Shell.  Run batch Emacs with -Q
flag.  Add line continuations to lines longer than 80 columns.
Don't generate dash.info.
* dash.info: Remove file.

create-docs.sh

@@ -1,13 +1,10 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
-if [ -z "$EMACS" ] ; then
-    EMACS="emacs"
+if [ -z "${EMACS}" ]; then
+    EMACS=emacs
 fi
 
-if [ -z "$MAKEINFO" ] ; then
-    MAKEINFO="makeinfo"
-fi
-
-$EMACS -batch -l dash.el -l dash-functional.el -l dev/examples-to-docs.el -l dev/examples.el -f create-docs-file
-$EMACS -batch -l dash.el -l dash-functional.el -l dev/examples-to-info.el -l dev/examples.el -f create-info-file
-$MAKEINFO --fill-column=70 dash.texi
+"${EMACS}" -Q -batch -l dash.el -l dash-functional.el \
+           -l dev/examples-to-docs.el -l dev/examples.el -f create-docs-file
+"${EMACS}" -Q -batch -l dash.el -l dash-functional.el \
+           -l dev/examples-to-info.el -l dev/examples.el -f create-info-file