refactor(docs): move all docs sources to a dedicated docs package (maxGraph#168)

Keep the former mxGraph documentation to allow a later documentation
migration.
Remove both the former mxGraph and the new maxGraph API docs as they can
be generated.
Remove the former mxGraph examples home page as it has been replaced by
Storybook.

Update the configuration to generate the maxGraph API docs
  - remove jsdoc resources as it is not used anymore
- configure the core package to generate the API docs in the docs
package
- add a GitHub workflow to ensure we can generate the API docs without
errors

Author: tbouffard

.github/workflows/generate-documentation.yml

@@ -0,0 +1,26 @@
+name: Generate documentation
+
+on:
+  pull_request:
+    branches:
+      - development
+    paths:
+      - '.github/workflows/generate-documentation.yml'
+      - 'packages/core/*'
+      - 'packages/docs/*'
+      - 'package.json'
+
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup node
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: '.nvmrc'
+      - name: Install dependencies
+        run: npm install
+      - name: Build @maxgraph/core API docs
+        working-directory: packages/core
+        run: npm run docs:api