Add Related Documentation section with links to Javadoc and Oracle docs

- Add 'docs' field to all 90 JSON files with curated links to
  Javadoc API references, JEP pages, and Oracle documentation
- All 112 unique URLs validated (no 404s)
- Create templates/doc-link.html for rendering doc links
- Add 'Related Documentation' section to slug template
- Add .docs-links and .doc-link CSS styling
- Update both Java and Python generators
- Update copilot-instructions.md schema
- Rebuild fat JAR

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: brunoborges

.github/copilot-instructions.md

@@ -82,6 +82,9 @@ Each `content/category/slug.json` file has this structure:
     "category/slug-1",
     "category/slug-2",
     "category/slug-3"
+  ],
+  "docs": [
+    { "title": "Javadoc or Guide Title", "href": "https://docs.oracle.com/..." }
   ]
 }
 ```
@@ -92,6 +95,7 @@ Each `content/category/slug.json` file has this structure:
 - `category` must match the parent folder name
 - `whyModernWins` must have exactly **3** entries
 - `related` must have exactly **3** entries (as `category/slug` paths)
+- `docs` must have at least **1** entry linking to Javadoc or Oracle documentation
 - `prev`/`next` are `category/slug` paths or `null` for first/last
 - Code in `oldCode`/`modernCode` uses `\n` for newlines
 

content/collections/collectors-teeing.json

@@ -40,5 +40,11 @@
     "collections/copying-collections-immutably",
     "collections/unmodifiable-collectors",
     "collections/stream-toarray-typed"
+  ],
+  "docs": [
+    {
+      "title": "Collectors.teeing()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/stream/Collectors.html#teeing(java.util.stream.Collector,java.util.stream.Collector,java.util.function.BiFunction)"
+    }
   ]
 }

content/collections/copying-collections-immutably.json

@@ -40,5 +40,11 @@
     "collections/immutable-set-creation",
     "collections/map-entry-factory",
     "collections/immutable-list-creation"
+  ],
+  "docs": [
+    {
+      "title": "List.copyOf()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/List.html#copyOf(java.util.Collection)"
+    }
   ]
 }

content/collections/immutable-list-creation.json

@@ -40,5 +40,15 @@
     "collections/immutable-map-creation",
     "collections/immutable-set-creation",
     "collections/sequenced-collections"
+  ],
+  "docs": [
+    {
+      "title": "List.of()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/List.html#of()"
+    },
+    {
+      "title": "Collections Factory Methods (JEP 269)",
+      "href": "https://openjdk.org/jeps/269"
+    }
   ]
 }

content/collections/immutable-map-creation.json

@@ -40,5 +40,15 @@
     "collections/copying-collections-immutably",
     "collections/sequenced-collections",
     "streams/stream-tolist"
+  ],
+  "docs": [
+    {
+      "title": "Map.of()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/Map.html#of()"
+    },
+    {
+      "title": "Map.ofEntries()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/Map.html#ofEntries(java.util.Map.Entry...)"
+    }
   ]
 }

content/collections/immutable-set-creation.json

@@ -40,5 +40,15 @@
     "collections/copying-collections-immutably",
     "collections/collectors-teeing",
     "streams/stream-tolist"
+  ],
+  "docs": [
+    {
+      "title": "Set.of()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/Set.html#of()"
+    },
+    {
+      "title": "Collections Factory Methods (JEP 269)",
+      "href": "https://openjdk.org/jeps/269"
+    }
   ]
 }

content/collections/map-entry-factory.json

@@ -40,5 +40,11 @@
     "collections/sequenced-collections",
     "collections/immutable-map-creation",
     "collections/immutable-list-creation"
+  ],
+  "docs": [
+    {
+      "title": "Map.entry()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/Map.html#entry(K,V)"
+    }
   ]
 }

content/collections/sequenced-collections.json

@@ -40,5 +40,15 @@
     "collections/collectors-teeing",
     "collections/immutable-set-creation",
     "collections/immutable-map-creation"
+  ],
+  "docs": [
+    {
+      "title": "Sequenced Collections (JEP 431)",
+      "href": "https://openjdk.org/jeps/431"
+    },
+    {
+      "title": "SequencedCollection",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/SequencedCollection.html"
+    }
   ]
 }

content/collections/stream-toarray-typed.json

@@ -40,5 +40,11 @@
     "collections/collectors-teeing",
     "collections/map-entry-factory",
     "collections/immutable-set-creation"
+  ],
+  "docs": [
+    {
+      "title": "Stream.toArray()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/stream/Stream.html#toArray(java.util.function.IntFunction)"
+    }
   ]
 }

content/collections/unmodifiable-collectors.json

@@ -40,5 +40,11 @@
     "collections/immutable-map-creation",
     "collections/immutable-set-creation",
     "collections/map-entry-factory"
+  ],
+  "docs": [
+    {
+      "title": "Collectors.toUnmodifiableList()",
+      "href": "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/stream/Collectors.html#toUnmodifiableList()"
+    }
   ]
 }