Fix docsify vulnerability

[alexandre-lelain]

Hello,

First of all, thank you for making this awesome library. I'm using it on a project and it really rocks.

The problem

There was a vulnerability spotted in one of docsify's dependency: marked.

WS-2019-0024
More information
moderate severity
Vulnerable versions: >= 0.5.0, < 0.6.1
Patched version: 0.6.1

A flaw was found in nodejs-marked versions from 0.5.0 to before 0.6.1. 
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS).
Input to the host variable is vulnerable when input contains parenthesis in link URIs, coupled with a high number of link tokens in a single line.

It was fixed in [email protected]: docsifyjs/docsify#934.

What this PR does

This PR bumps the version of docsify (previously >=3) to the version ^4.10.2 to fix the vulnerabilities audited in the project by npm.

The snapshots tests were updated accordingly.

[anikethsaha]

🎉