feat: New page for OpenAPI security features

[SensibleWood]

This PR addresses Issue #74.

Summary of changes:

• Added Security page to specification directory.
• Provided overview of Security Scheme Object and Security Requirement Object and relationship between both.
• Provided details on each security type with examples inlne.
• Updated tictactoe OpenAPI document with examples.
• Added a note to README on running Jekyll and pointer to Contributing Guide.
• Updated link to this repository in _config.yml.
• Added diagram to represent security-related objects in digraph and SVG formats.

👍 cc @lornajane

[handrews]

This looks good! I particularly like how you called attention to how the OAS intentionally includes only the minimum necessary information.

I had one grammar nitpick, and also one suggestion that you are free to disregard. Otherwise I'm in favor of merging this.

[miqui]

@SensibleWood - have you seen this: https://swagger.io/docs/specification/authentication/

I think this is very similar to what you are proposing.

[SensibleWood]

@SensibleWood - have you seen this: https://swagger.io/docs/specification/authentication/

I think this is very similar to what you are proposing.

Yes I have read it before. I would expect there is some commonality given they are both intended to be reference materials

[ralfhandl]

"based on a theme based on [a] theme" - really that indirect?

[ralfhandl]

Suggested change

	<p>Original site customized based on a theme based on theme by Patrick Marsceill, distributed by an <a href="https://github.com/pmarsceill/just-the-docs/tree/master/LICENSE.txt">MIT license.</a></p>
	<p>Original site customized based on a theme by Patrick Marsceill, distributed by an <a href="https://github.com/pmarsceill/just-the-docs/tree/master/LICENSE.txt">MIT license.</a></p>

[SensibleWood]

I didn't write that sentence nor sourced the theme so can't say whether the indirection is accurate or not...

[lornajane]

let's open a separate issue for this part - it's a good point (thanks @ralfhandl !) but it's not related to the work in this pull request.

[darrelmiller]

This doc page is a great. Thank you!