(chore): remove unused mkdocs.yml (#798)

mkdocs.yml

@@ -1,40 +0,0 @@
-site_name: "Org-roam"
-repo_url: https://github.com/org-roam/org-roam/
-edit_uri: edit/master/doc/
-copyright: "Copyright (C) 2020 Jethro Kuan and contributors"
-docs_dir: doc
-extra:
-  social:
-    - type: 'slack'
-      link: 'https://join.slack.com/t/orgroam/shared_invite/zt-clh0g0tx-j8xg1kVxnrWdKt16gmSGPQ'
-nav:
-- Home: index.md
-- A Tour of Org-roam: tour.md
-- Installation: installation.md
-- Configuration: configuration.md
-- Anatomy of an Org-roam file: anatomy.md
-- The Templating System: templating.md
-- Ecosystem: ecosystem.md
-- Similar Packages: comparison.md
-- "Appendix: Note-taking Workflow": notetaking_workflow.md
-- "Appendix: Roam Protocol": roam_protocol.md
-- "Appendix: Org Export": org_export.md
-markdown_extensions:
-  - admonition
-  - pymdownx.betterem:
-      smart_enable: all
-  - pymdownx.caret
-  - pymdownx.critic
-  - pymdownx.details
-  - pymdownx.mark
-  - pymdownx.smartsymbols
-  - pymdownx.superfences
-  - pymdownx.tasklist:
-      custom_checkbox: true
-  - pymdownx.tilde
-
-theme:
-  name: 'material'
-  palette:
-    primary: 'deep purple'
-    accent: 'deep purple'