Add misspell check (#94)

* Add misspell check via ReviewDog

see: https://github.com/reviewdog/action-misspell

misspell: https://github.com/client9/misspell

* Use default misspell locale, not US

> Default is to use a neutral variety of English.  Setting locale to US
> will correct the British spelling of 'colour' to 'color' [1]

[1] https://github.com/client9/misspell

.github/workflows/reviewdog.yml

@@ -44,3 +44,13 @@ jobs:
           path: "."
           pattern: "*.sh"
           exclude: "./.git/*"
+
+  misspell:
+    name: runner / misspell
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: reviewdog/action-misspell@v1
+        with:
+          github_token: ${{ secrets.github_token }}
+          reporter: github-check