Add codespell

.codespellrc

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+[codespell]
+skip = Gemfile,Gemfile.lock,jekyll-assets,build
+# For a list of available built-in dictionaries, see:
+#  https://github.com/codespell-project/codespell/tree/master/codespell_lib/data
+builtin = clear,rare,informal
+ignore-words-list = technic,ba,hist

.github/workflows/codespell.yml

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+---
+name: Check for common misspellings
+
+on:
+  push:
+  pull_request:
+    branches: [develop]
+
+jobs:
+  codespell:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Check spelling with codespell
+        # Configuration should be handled in .codespellrc as much as possible so
+        # that it runs similarly locally
+        uses: codespell-project/actions-codespell@master
+        with:
+          # Annotate the build, but don't fail it
+          only_warn: 1