Feedback button disabled by default without config option set despite defaults set to enabled

[SecondSkoll]

Because the feedback button is only added if specific settings are found:

if html_context.get("github_issues") and not disable_feedback_button:
        html_js_files.append("github_issue_links.js")

And the defaults are set afterwards, the feedback button is not added to documentation by default as is intended.

Current workaround is to provide 'github_issues': 'enabled', in html_context in the configuration file.

[jahn-junior]

Resolved in #97.

Testing on the most recent version shows that the feedback button is enabled by default.