Add spellcheck gh action

Author: Philip Laine

.github/workflows/pr-validate.yaml

@@ -1,20 +1,28 @@
-name: PR Validation
-
+name: PR Validate
 on: pull_request
-
 jobs:
-  build:
+  spellcheck:
+    name: spellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Run spellcheck
+        uses: rojopolis/spellcheck-github-actions@0.16.0
+  markdownlint:
     name: markdownlint-cli
     runs-on: ubuntu-latest
-
     steps:
       - name: Checkout Code
         uses: actions/checkout@v2
         with:
           fetch-depth: 0
-
       - uses: actions/setup-node@v2
         with:
           node-version: "16"
-      - run: npm install markdownlint-cli
-      - run: make markdownlint
+      - name: Install markdownlint
+        run: npm install markdownlint-cli
+      - name: Run markdownlint
+        run: make markdownlint