Breadcrumb links should be encoded as local path not external URLs

[chalin]

Currently, links in breadcrumbs are encoded as external URLs, even if they are obviously site-local paths. This causes the following problems:

• When working on docsy sites served from Cloud editors like those offered by GitPod. The "external" links encoded in the breadcrumbs don't actually correspond to the URL the site is served from -- which can be of the form https://1313-foo-bee-doo.ws-us79.gitpod.io.
• External link checking is unnecessarily burdened (which leads to timeouts etc) for external links that are actually both site-local and unlikely to be invalid.

I thought that we had an issue open over this before, but can't find any. Having previously investigated this, there doesn't seem to be a hard requirement (contrary to what is state in some articles), that breadcrumb links be full URLs.

[chalin]

Another option is to use link-checker ignore attributes. E.g., see:

• Support link-checker ignore attribute for last-mod links #1432

[chalin]

@fekete-robert - funny thing, if you check the Docsy website now, the breadcrumbs are relative :)

$ curl -s https://www.docsy.dev/docs/get-started/ | perl -ne 'print $& if /<li class="?breadcrumb-item"?>.*?<\/li>/'
<li class=breadcrumb-item><a href=/docs/>Documentation</a></li>

But that's due to another issue that I'll fix shortly.