Add action validating OpenAPI (swagger) spec.

Adapted action from this posting: https://swagger.io/blog/api-design/validate-openapi-definitions-swagger-editor/

.github/workflows/api-spec.yml

@@ -0,0 +1,24 @@
+# Adapted from this posting:
+# https://swagger.io/blog/api-design/validate-openapi-definitions-swagger-editor/
+
+on: 
+  push:
+    branches:
+      - '**'
+  pull_request:
+    branches:
+      - master
+
+
+jobs:
+  test_swagger_editor_validator_remote:
+    runs-on: ubuntu-latest
+    name: Swagger Editor Validator Remote
+
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Validate OpenAPI definition
+        uses: char0n/swagger-editor-validate@v1
+        with:
+          definition-file: src/main/resources/docs/swagger.yaml