Improved Nested Docs and Link Grouping Support (#147)

* added a table of content

* wide layout for docs, styles for the table of content

* fixes for docs layout

* wide footer at the docs section

* added support for nested docs, added toggling groups of links, delimiters, external links

* external link icon

* added active state for nested links, styles for the external link icon

* styles fix

* remove doc sync

* update directory structure and doc titles

* fix outstanding links

* fix more links for merge

* Revert "fix more links for merge"

This reverts commit 46c9ccaf1b7765f2cda8dc85d625fa6b4e3f5436.

* Revert "fix outstanding links"

This reverts commit 28e6380b74f1ab74690c8184551f186656d6d4e9.

* fix remaining broken links

* move how-to tutorials in the different page

* split tutorials

* fix link

* upd github edit link

* skip empty index pages

---------

Co-authored-by: Andrey Vasnetsov <andrey@vasnetsov.com>
Co-authored-by: David Sertic <62056091+davidmyriel@users.noreply.github.com>

qdrant-landing/content/stack/1_open-ai.md

@@ -1,6 +1,6 @@
 ---
 image: "content/images/logos/open-ai-logo"
-origin_url: "https://qdrant.tech/documentation/integrations/#openai"
+origin_url: "https://qdrant.tech/documentation/integrations/openai"
 name: "OpenAI"
 sitemapExclude: True
 ---