test: write test case for --version flag

Author: jamesgeorge007

e2e/index.js

@@ -18,4 +18,5 @@ const matchSnapshot = async (t, arg) => {
 
 test('shows help with -h flag', matchSnapshot, '-h');
 test('shows help with --help flag', matchSnapshot, '--help');
-test('shows help with -v flag', matchSnapshot, '-v');
+test('shows help with -v flag', matchSnapshot, '-v');
+test('shows help with --version flag', matchSnapshot, '--version');

e2e/index.js.md

@@ -80,3 +80,12 @@ Generated by [AVA](https://ava.li).
       https://github.com/docsifyjs/docsify-cli/blob/master/CONTRIBUTING.md␊
     ␊
     [ERROR] 0 arguments passed. Please specify a command`
+
+## shows help with --version flag
+
+> Snapshot 1
+
+    `␊
+    docsify-cli version:␊
+      4.4.0␊
+    `