Revert back to expanded workflow

.github/workflows/readthedocs-pr-update.yml

@@ -16,16 +16,26 @@ permissions:
   pull-requests: write
 
 jobs:
-  documentation:
+  graphs-documentation:
+    if: contains(github.event.pull_request.files.*.path, 'graphs/docs/')
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        project:
-          - { path: 'graphs/docs/', slug: 'anemoi-graphs' }
-          - { path: 'models/docs/', slug: 'anemoi-models' }
-          - { path: 'training/docs/', slug: 'anemoi-training' }
-    if: contains(github.event.pull_request.files.*.path, matrix.project.path)
     steps:
       - uses: readthedocs/actions/preview@v1
         with:
-          project-slug: ${{ matrix.project.slug }}
+          project-slug: "anemoi-graphs"
+
+  models-documentation:
+    if: contains(github.event.pull_request.files.*.path, 'models/docs/')
+    runs-on: ubuntu-latest
+    steps:
+      - uses: readthedocs/actions/preview@v1
+        with:
+          project-slug: "anemoi-models"
+
+  training-documentation:
+    if: contains(github.event.pull_request.files.*.path, 'training/docs/')
+    runs-on: ubuntu-latest
+    steps:
+      - uses: readthedocs/actions/preview@v1
+        with:
+          project-slug: "anemoi-training"