.github/workflows/docs.yml: add workflow to check links in docs

.github/workflows/docs.yml

@@ -0,0 +1,32 @@
+name: Docs check
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - 'docs/**'
+  pull_request:
+    paths:
+      - 'docs/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  docs:
+    name: Check Docs
+    runs-on: ubuntu-latest
+    container:
+      image: ghcr.io/void-linux/void-linux:latest-full-x86_64
+    steps:
+      - name: Prepare container
+        run: |
+          xbps-install -Syu || xbps-install -y xbps
+          xbps-install -yu
+          xbps-install -y chroot-git make
+      - uses: actions/checkout@master
+      - name: Prepare environment
+        run: cd docs && make SUDO= INSTALLOPTS=-yu setup-void
+      - name: Linkcheck
+        run: cd docs && make SPHINXOPTS=--color linkcheck

docs/Makefile

@@ -7,6 +7,7 @@ VENV          ?= env
 PIP_FLAGS     ?= -q
 SERVEOPTS     ?=
 SUDO          ?= sudo
+INSTALLOPTS   ?= -Su
 SOURCEDIR     = .
 BUILDDIR      = _build
 
@@ -29,7 +30,7 @@ gen-man: man
 	@cp -r $(BUILDDIR)/man $(SOURCEDIR)/man/dist
 
 setup-void:
-	@$(SUDO) xbps-install -Su $(VOID_PKGS)
+	@$(SUDO) xbps-install $(INSTALLOPTS) $(VOID_PKGS)
 
 setup: $(VENV)/req_done