chore: publish rustdoc output to GitHub Pages

Author: bavshin-f5

.github/workflows/docs.yaml

@@ -0,0 +1,63 @@
+name: docs (dev)
+
+on:
+  push:
+    branches: [github-pages]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout source
+        uses: actions/checkout@v3
+      - name: set up cargo cache
+        uses: actions/cache@v3
+        continue-on-error: false
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-
+      - name: set up nginx deps cache
+        uses: actions/cache@v3
+        continue-on-error: false
+        with:
+          path: |
+            .cache/.gnupg
+            .cache/nginx
+            .cache/*.tar.gz
+            .cache/*.tar.asc
+            .cache/*.tar.sig
+          key: ${{ runner.os }}-deps-${{ hashFiles('**/nginx-sys/build.rs') }}
+          restore-keys: ${{ runner.os }}-deps-
+      - name: build docs
+        run: cargo doc --no-deps --workspace
+      - name: create index page
+        run: echo '<meta http-equiv="refresh" content="1;url=ngx/index.html"/>' > target/doc/index.html
+      - name: upload docs artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: "target/doc"
+
+  deploy:
+    needs: build
+
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+
+    permissions:
+      pages: write
+      id-token: write
+
+    runs-on: ubuntu-latest
+    steps:
+      - id: deployment
+        uses: actions/deploy-pages@v4

README.md

@@ -1,4 +1,5 @@
 [![Rust](https://github.com/nginx/ngx-rust/actions/workflows/ci.yaml/badge.svg)](https://github.com/nginx/ngx-rust/actions/workflows/ci.yaml)
+[![docs (dev)](https://github.com/bavshin-f5/ngx-rust/actions/workflows/docs.yaml/badge.svg?branch=master)](https://bavshin-f5.github.io/ngx-rust/ngx/index.html)
 [![crates.io](https://img.shields.io/crates/v/ngx.svg)](https://crates.io/crates/ngx)
 [![Project Status: Concept – Minimal or no implementation has been done yet, or the repository is only intended to be a limited example, demo, or proof-of-concept.](https://www.repostatus.org/badges/latest/concept.svg)](https://www.repostatus.org/#concept)
 [![Community Support](https://badgen.net/badge/support/community/cyan?icon=awesome)](https://github.com/nginx/ngx-rust/discussions)