Add API overview page for SVG

[wbamberg]

GroupData.json lists "SVG" as a Web API, but it doesn't have an API overview page. We should write a page and add the "overview" property to GroupData.

[himanshugarg]

Does this qualify for an API overview page?

[hamishwillee]

@himanshugarg Nearly. I believe the criteria would be that it is under https://developer.mozilla.org/en-US/docs/Web/API/ and https://developer.mozilla.org/en-US/docs/MDN/Structures/Page_types/API_landing_page_template

@wbamberg perhaps we could move/redirect it, update it to match the template. I prefer fewer entry points unless they have a significantly different audience and hence content.

[wbamberg]

It's not really an API overview page. It's a top-level overview page (and navigation root) for the SVG technology as a whole, which is mostly expressed as a set of XML-based elements and attributes (just as HTML is).

API overview pages are part of the "Web API" domain, which is a set of specifications describing the JavaScript interfaces implemented in browsers. What we're missing is an overview page for the interfaces that browsers provide that enable JavaScript running in web pages to interact with SVG elements.

These things have a pretty standard structure, consisting of a short overview, a list of all the interfaces, and a spec table. For example: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API.

A rough analogy would be with https://developer.mozilla.org/en-US/docs/Web/CSS and https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model.