BUG: Documentation: Backslashes in help for list|ls need to be escaped

As parameter extension is active in the here-document.
Escape the literal "$" as well; not needed, but better style.

Fixes #472

Author: inkarkat

todo.sh

@@ -219,11 +219,11 @@ actionsHelp()
 		      Displays all tasks that contain TERM(s) sorted by priority with line
 		      numbers.  Each task must match all TERM(s) (logical AND); to display
 		      tasks that contain any TERM (logical OR), use
-		      'TERM1\|TERM2\|...' (with quotes), or TERM1\\\|TERM2 (unquoted).
+		      'TERM1\\|TERM2\\|...' (with quotes), or TERM1\\\\\\|TERM2 (unquoted).
 		      Hides all tasks that contain TERM(s) preceded by a
 		      minus sign (i.e. -TERM).
 		      TERM(s) are grep-style basic regular expressions; for literal matching,
-		      put a single backslash before any [ ] \ $ * . ^ and enclose the entire
+		      put a single backslash before any [ ] \\ \$ * . ^ and enclose the entire
 		      TERM in single quotes, or use double backslashes and extra shell-quoting.
 		      If no TERM specified, lists entire todo.txt.