docs: Add comprehensive Wiki.js version compatibility documentation

Add detailed compatibility documentation and version detection:

- Add Wiki.js 2.x compatibility badge and requirements to README
- Create comprehensive docs/compatibility.md guide
  - Detailed version support matrix (2.2 through 2.5.308+)
  - API schema differences between 2.x and 3.x
  - Version detection examples and troubleshooting
  - Known compatibility issues and solutions
  - Future 3.x support planning
- Enhance test_connection() in both sync and async clients
  - Add API version compatibility detection
  - Better error messages for incompatible versions
  - Detect Wiki.js 3.x and provide clear guidance
- Update package metadata
  - Add Wiki.js compatibility keywords to setup.py and pyproject.toml
  - Add compatibility documentation link to project URLs

SDK supports Wiki.js 2.x (versions 2.2 - 2.5.308+)
Wiki.js 3.x (alpha) not yet supported due to different API schema

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

setup.py

@@ -54,6 +54,8 @@ setup(
         "Bug Reports": "https://gitea.hotserv.cloud/lmiranda/py-wikijs/issues",
         "Source": "https://gitea.hotserv.cloud/lmiranda/py-wikijs",
         "Documentation": "https://gitea.hotserv.cloud/lmiranda/py-wikijs/src/branch/main/docs",
+        "Compatibility": "https://gitea.hotserv.cloud/lmiranda/py-wikijs/src/branch/main/docs/compatibility.md",
+        "Wiki.js": "https://js.wiki",
     },
     packages=find_packages(),
     include_package_data=True,
@@ -84,6 +86,6 @@ setup(
         "Topic :: Documentation",
         "Typing :: Typed",
     ],
-    keywords=["wiki", "wikijs", "api", "sdk", "client", "http", "rest"],
+    keywords=["wiki", "wikijs", "wiki.js", "api", "sdk", "client", "http", "rest", "graphql", "wiki.js-2.x"],
     zip_safe=False,
 )