Added promptListTitle to README.md

Author: azmizar

README.md

@@ -113,6 +113,7 @@ Property | Type | Required | Comment
  endIfEmpty | boolean | Y | True will end prompt session if user enter empty string `''`
  valueToEndPrompt | string | N | Future used?
  prompt | string | Y | Prompt text
+ promptListTitle | string | B | Prompt list title
  promptList | PromptItem[] | N | List of prompt options
 
 > ### PromptItem
@@ -142,4 +143,4 @@ Property | Type |  Comment
 * [Issues](https://github.com/simplyappdevs/nodejs-prompt/issues)
 * [Developer](https://www.simplyappdevs.com)
 
-Brought to you by www.simplyappdevs.com (2020)
+Brought to you by www.simplyappdevs.com (2020)