Add initial linting GitHub Action workflow

Note that this only catches lint issues in the script for now.

Closes #4

Author: EdricChan03

.github/workflows/main.yml

@@ -0,0 +1,13 @@
+name: Main Workflow
+
+on: push
+
+jobs:
+  shellcheck:
+    name: Lint Action script
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Run shellcheck command
+      uses: ludeeus/[email protected]