Migrate to using docusaurus, rather than docsify for documentation (#603)

* Add docusaurus documentation (to replace the docsify setup
* Remove older docs
* Specify documentation as the gh pages build action working directory

.github/workflows/github_pages_deploy.yml

@@ -0,0 +1,37 @@
+name: build and deploy github pages for documentation
+on:
+  push:
+    branches:
+      - 'master'
+
+jobs:
+    deploy:
+      environment:
+        name: github-pages
+        url: https://docs.khoj.dev
+      runs-on: ubuntu-latest
+      steps:
+        - name: Checkout
+          uses: actions/checkout@v3
+        # 👇 Build steps
+        - name: Set up Node.js
+          uses: actions/setup-node@v3
+          with:
+            node-version: 16.x
+            cache: yarn
+        - name: Install dependencies
+          working-directory: documentation
+          run: yarn install --frozen-lockfile --non-interactive
+        - name: Build
+          run: yarn build
+        # 👆 Build steps
+        - name: Setup Pages
+          uses: actions/configure-pages@v3
+        - name: Upload artifact
+          uses: actions/upload-pages-artifact@v2
+          with:
+            # 👇 Specify build output path
+            path: build
+        - name: Deploy to GitHub Pages
+          id: deployment
+          uses: actions/deploy-pages@v2