test: rake build_multi

Author: toshimaru

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
 
   doc-build-latest:
     runs-on: ubuntu-latest
-    name: Rails Doc Build
+    name: Rails Doc Build (latest)
     steps:
     - uses: actions/checkout@v3
       with:
@@ -27,5 +27,18 @@ jobs:
         ruby-version: 3.1
         bundler-cache: true
     - name: Doc Build
-      run: |
-        rake build
+      run: rake build
+
+  doc-build-others:
+    runs-on: ubuntu-latest
+    name: Rails Doc Build (older versions)
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: true
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 2.7
+        bundler-cache: true
+    - name: Doc Build
+      run: rake build_multi