Add GitHub Action to check spelling (#3591)

Signed-off-by: Aaron Raimist <aaron@raim.ist>

.github/_typos.toml

@@ -0,0 +1,12 @@
+[files]
+extend-exclude = ["/themes", "/attic", "/data-definitions", "*.css", "package-lock.json"]
+
+[default]
+check-filename = true
+
+[default.extend-identifiers]
+au1ba7o = "au1ba7o"
+
+[default.extend-words]
+Appy = "Appy"
+fo = "fo"

.github/workflows/spell-check.yaml

@@ -0,0 +1,15 @@
+name: Spell Check
+on: [pull_request]
+
+jobs:
+  run:
+    name: Spell Check with Typos
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout Actions Repository
+      uses: actions/checkout@v2
+
+    - name: Check spelling of proposals
+      uses: crate-ci/typos@master
+      with:
+        config: ${{github.workspace}}/.github/_typos.toml