GHA: run proselint on markdown files

Co-authored-by: Marc Hörsken

Closes #9520

.github/workflows/proselint.yml

@@ -0,0 +1,62 @@
+# Copyright (C) 2022 Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# SPDX-License-Identifier: curl
+
+name: proselint
+
+on:
+  push:
+    branches:
+    - master
+    - '*/ci'
+    paths:
+    - '.github/workflows/proselint.yml'
+    - '**.md'
+  pull_request:
+    branches:
+    - master
+    paths:
+    - '.github/workflows/proselint.yml'
+    - '**.md'
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: install prereqs
+      run: sudo apt-get install python3-proselint
+
+    # config file help: https://github.com/amperser/proselint/
+    - name: create proselint config
+      run: |
+        cat <<JSON > $HOME/.proselintrc
+        {
+          "checks": {
+            "typography.diacritical_marks": false,
+            "typography.symbols": false,
+            "annotations.misc": false
+          }
+        }
+        JSON
+
+    - name: check prose
+      run: a=`git ls-files '*.md' | grep -v docs/CHECKSRC.md` && proselint $a README
+
+    # This is for CHECKSRC and files with aggressive exclamation mark needs
+    - name: create second proselint config
+      run: |
+        cat <<JSON > $HOME/.proselintrc
+        {
+          "checks": {
+            "typography.diacritical_marks": false,
+            "typography.symbols": false,
+            "typography.exclamation": false,
+            "annotations.misc": false
+          }
+        }
+        JSON
+
+    - name: check special prose
+      run: a=docs/CHECKSRC.md && proselint $a