chore(workflow): add basic spell checking

.github/workflows/pr-validate.yml

@@ -31,3 +31,16 @@ jobs:
         with:
           name: oscal.io-content
           path: _site
+  spellcheck:
+    name: Check spelling
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          submodules: 'recursive'
+      - name: Spell check
+        uses: rojopolis/spellcheck-github-actions@0.30.0
+      - name: Check wordlist.txt is sorted
+        run: |
+          sort -fu .wordlist.txt | diff -Nau .wordlist.txt -

.spellcheck.yml

@@ -0,0 +1,29 @@
+matrix:
+  - name: Markdown
+    aspell:
+      ignore-case: true
+      lang: en
+    dictionary:
+      wordlists:
+        - .wordlist.txt
+      encoding: utf-8
+    pipeline:
+      - pyspelling.filters.context:
+          context_visible_first: true
+          escapes: '\\[\\`~]'
+          delimiters:
+          # Ignore multiline content between fences (fences can have 3 or more back ticks)
+          # ```
+          # content
+          # ```
+          - open: '(?s)^(?P<open> *-{3,})$'
+            close: '^(?P=open)$'
+      - pyspelling.filters.markdown:
+      - pyspelling.filters.html:
+          comments: false
+          ignores:
+            - code
+            - pre
+    sources:
+      - '_tools/*.md'
+      - '_events/*.md'

.wordlist.txt

@@ -0,0 +1,10 @@
+ATO
+FedRAMP
+Javan
+NIST
+OSCAL
+Pirooz
+SSPs
+https
+liboscal
+usnistgov