Docs: the markdown file was not rendered to html file in master-commandline-reference.html

[ChaoyiHuang]

What happened:

In the docuement, https://kubernetes-sigs.github.io/node-feature-discovery/v0.16/reference/master-commandline-reference.html, the feature gates documenation is linked to feature-gates.md, and will return 404 if clicking the link.

What you expected to happen:

It should link to a rendered feature-gates.html, so that when click the link, a propoer html page could be jumped to.

How to reproduce it (as minimally and precisely as possible):

1. visit: https://kubernetes-sigs.github.io/node-feature-discovery/stable/get-started/index.html
2. visit: https://kubernetes-sigs.github.io/node-feature-discovery/v0.16/reference/master-commandline-reference.html
3. click the hyperlink: feature gates documentation.

Anything else we need to know?:
NA

Environment:

• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others:

[ChaoyiHuang]

Closed by PR: #1821