patch 9.1.0741: No way to get prompt for input()/confirm()

Problem:  No way to get prompt for input()/confirm()
Solution: add getcmdprompt() function (Shougo Matsushita)
          (Shougo Matsushita)

closes: #15667

Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index 9d22521..94e662d 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -41608,6 +41608,7 @@
 |diff()|		diff two Lists of strings
 |filecopy()|		copy a file {from} to {to}
 |foreach()|		apply function to List items
+|getcmdprompt()|        get prompt for input()/confirm()
 |getregion()|		get a region of text from a buffer
 |getregionpos()|	get a list of positions for a region
 |id()|			get unique identifier for a Dict, List, Object,