docs: restructure and add more content (#2232)

* docs: restructure quickstarts

* docs: quickstart libs

* docs: add exlixir lib

* docs: restructure

* docs: restructure

* docs: customization

* use tabs in oauth/oidc endpoints.md

* improve authorize_endpoint

* improve token_endpoint and introspection_endpoint

* docs: saas use case

* styling

* styling

* begin login users

* login users

* login users

* fix table

* fix: links

* fix: links

* start go api

* fix: policy structure

* fix: saas description

* fix: saas description

* fix: saas description

* Update docs/docs/concepts/policies.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* Update docs/docs/concepts/usecases/saas.md

Co-authored-by: mffap <mpa@caos.ch>

* docs: organisation --> organization

* docs: fixes

* docs: fixes

* Update docs/docs/apis/openidoauth/endpoints.md

Co-authored-by: Florian Forster <florian@caos.ch>

* Update docs/docs/concepts/policies.md

Co-authored-by: Florian Forster <florian@caos.ch>

* Update docs/docs/concepts/policies.md

Co-authored-by: Florian Forster <florian@caos.ch>

* Update docs/docs/concepts/policies.md

Co-authored-by: Florian Forster <florian@caos.ch>

* Update docs/docs/apis/openidoauth/endpoints.md

Co-authored-by: Florian Forster <florian@caos.ch>

* Apply suggestions from code review

Co-authored-by: Florian Forster <florian@caos.ch>

* docs: intro

* Update docs/docs/guides/customization/branding.md

Co-authored-by: Florian Forster <florian@caos.ch>

* fix: typo

* add mermaid

Co-authored-by: Livio Amstutz <livio.a@gmail.com>
Co-authored-by: mffap <mpa@caos.ch>
Co-authored-by: Florian Forster <florian@caos.ch>

docs/package.json

@@ -19,6 +19,8 @@
     "@mdx-js/react": "^1.6.22",
     "clsx": "^1.1.1",
     "docusaurus-plugin-plausible": "^0.0.5",
+    "mdx-mermaid": "^1.1.0",
+    "mermaid": "^8.12.1",
     "react": "^17.0.2",
     "react-dom": "^17.0.2"
   },