Improvements to breadcrumb navigation paths

[lyswhut]

for examples:

The full breadcrumb path for this page should be: home > Docs > Introduction
But now it is: home > Introduction

The full breadcrumb path for this page should be: home > API > Client API
But now it is: home > Client API

[slorber]

What you ask for doesn't make sense in all cases.

This is discussed and tracked here: #6953