ci: rename all github actions workflow files, that are related to CI (run on commits/PRs), to have a _ci.yml postfix

.github/workflows/module_docs_ci.yml

@@ -0,0 +1,20 @@
+name: vlib modules CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  build-module-docs:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build V
+        run: make
+      - name: Build module documentation
+        run: ./v doc -m -f html vlib/
+      - name: Deploy docs to vercel
+        if: ${{ github.event_name == 'push' }}
+        run: npx vercel --confirm --prod --name vmodules --token ${{ secrets.VERCEL_TOKEN }} vlib/_docs/ || true