Release 0.2.0

This is release 0.2.0, the first stable release of Colmena!

---

Colmena is a simple, stateless NixOS deployment tool modeled
after NixOps and morph. In particular, it is built from the
ground up to support parallelization of the steps in the
deployment process.

This release contains the following features:

- Node Tagging
- Local Deployment
- Secrets
- Ad Hoc Evaluation
- Nix Flakes Support
- Parallelism

We now have a User Manual at <https://zhaofengli.github.io/colmena/0.2>
containing tutorials, sample configurations as well as a
complete listing of supported deployment options.

Signed-off-by: Zhaofeng Li <hello@zhaofeng.li>

.github/workflows/manual-stable.nix

@@ -0,0 +1,62 @@
+name: Manual (Stable)
+
+on:
+  push:
+    branches:
+      - release-0.2.x
+jobs:
+  deploy:
+    env:
+      LATEST_STABLE_API: 0.2
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2.3.5
+      - uses: cachix/install-nix-action@v15
+        with:
+          install_url: https://releases.nixos.org/nix/nix-2.4/install
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+      - uses: cachix/cachix-action@v10
+        with:
+          name: colmena
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+
+      - name: Check API version
+        run: echo "api_version=$(nix eval .#colmena.apiVersion)" >> $GITHUB_ENV
+
+      # == Manual
+      - name: Build manual
+        run: nix build -o out .#manual -L
+
+      # Ugly hack so it has permission to delete the worktree afterwards
+      - name: Copy manual
+        run: cp --no-preserve=mode -r out/ public/
+
+      - name: Deploy manual
+        uses: JamesIves/github-pages-deploy-action@4.1.5
+        with:
+          branch: gh-pages
+          folder: public
+          target-folder: '${{ env.api_version }}'
+
+      # == Redirect Farm for Latest Stable
+      # /stable -> /api_version
+
+      - name: Build redirect farm
+        run: nix build -o out .#manual.redirectFarm -L
+        if: ${{ env.api_version == env.LATEST_STABLE_API }}
+
+      # Ugly hack so it has permission to delete the worktree afterwards
+      - name: Copy redirect farm
+        run: cp --no-preserve=mode -r out-redirectFarm/ redirect-farm/
+        if: ${{ success() }}
+
+      - name: Deploy redirect farm
+        uses: JamesIves/github-pages-deploy-action@4.1.5
+        with:
+          branch: gh-pages
+          folder: redirect-farm
+          target-folder: stable
+        if: ${{ success() }}