docs: use relative URLs in documentation

[umdstu]

Related to angular/material.angular.io#623, the docs all have routes to other components hard-coded to the https://material.angular.io domain, rather than relative to the hosted documentation.

Please update them to use relative routes.

[Splaktar]

Can you please provide an example?

[umdstu]

My apologies for the delay, I was away.

For example, https://github.com/angular/material2-docs-content/blob/master/docs-content/overviews/cdk/table.html

Links directly to https://material.angular.io/components/table, but I imagine it should be
/components/table perhaps.

[Splaktar]

OK, that table.html file is generated from https://github.com/angular/components/blob/b24308caa304a5a8a534940ca407672945db4d9b/src/cdk/table/table.md. So this issue should be filed against the angular/components repo. I'll transfer it over there.

I think that the issues with the docs site were fixed by PR angular/material.angular.io#643 which closed angular/material.angular.io#623.

But there are still docs in the angular/components repo that introduce absolute URLs instead of relative URLs. It would be helpful if we could track down a full list of offending .md files.

[devversion]

I think we need a general concept of referencing other docs from overviews and guides. The problem seems that the ultimate page URLs are constructed by material.angular.io, so it's difficult to figure out what the other URLs are when writing in markdown (in the angular/components repo).

We should think more about this. This would eventually also allow us to get rid of such fixups:

components/tools/markdown-to-html/docs-marked-renderer.ts

Lines 37 to 44 in 09dc459

	link(href: string, title: string, text: string) {
	// We only want to fix up markdown links that are relative and do not refer to guides already.
	// Otherwise we always map the link to the "guide/" path.
	// TODO(devversion): remove this logic and just disallow relative paths.
	if (!href.startsWith('http') && !href.startsWith('#') && !href.includes('guide/')) {
	return super.link(`guide/${basename(href, extname(href))}`, title, text);
	}