CI: generate docs and display "builds" badge in README

Author: pazz

.github/workflows/docs.yml

@@ -0,0 +1,28 @@
+name: Docs
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+
+jobs: 
+  docs: 
+    runs-on: ubuntu-latest 
+
+    steps: 
+    - uses: actions/checkout@v2 
+    - name: Set up Rust 
+      uses: actions-rs/toolchain@v1 
+      with: 
+        toolchain: stable 
+        profile: minimal 
+        override: true 
+    - name: Cache Cargo dependencies
+      uses: Swatinem/rust-cache@v2
+    - name: Generate docs
+      run: cargo doc
+
+
+# TODO: deploy these somewhere?

README.md

@@ -2,8 +2,9 @@
 
 <!-- badges: start -->
 [![made-with-rust](https://img.shields.io/badge/Made%20with-Rust-1f425f.svg)](https://www.rust-lang.org/)
-[![Build](https://github.com/SynthesisLab/shepherd/actions/workflows/build.yaml/badge.svg?branch=main&event=push)](https://github.com/SynthesisLab/shepherd/actions/workflows/build.yaml)
-[![Tests](https://github.com/SynthesisLab/shepherd/actions/workflows/test.yaml/badge.svg?branch=main&event=push)](https://github.com/SynthesisLab/shepherd/actions/workflows/test.yaml)
+[![Build](https://github.com/SynthesisLab/shepherd/actions/workflows/build.yml/badge.svg?branch=main&event=push)](https://github.com/SynthesisLab/shepherd/actions/workflows/build.yml)
+[![Docs](https://github.com/SynthesisLab/shepherd/actions/workflows/docs.yml/badge.svg?branch=main&event=push)](https://github.com/SynthesisLab/shepherd/actions/workflows/docs.yml)
+[![Tests](https://github.com/SynthesisLab/shepherd/actions/workflows/test.yml/badge.svg?branch=main&event=push)](https://github.com/SynthesisLab/shepherd/actions/workflows/test.yml)
 <!-- badges: end -->