docs: use pyd4vinci/scrapling in remaining Docker examples (#282)

PR #283 fixed the bare `scrapling` image name in docs/ai/mcp-server.md;
the agent-skill MCP reference and CLI extract docs still used the
unqualified name, which Docker resolves against the official library
namespace and fails with pull access denied.

docs/cli/extract-commands.md

@@ -50,7 +50,7 @@ The extract command is a set of simple terminal tools that:
     scrapling extract get "https://example.com" content.txt
   
     # Or use the Docker image with something like this:
-    docker run -v $(pwd)/output:/output scrapling extract get "https://blog.example.com" /output/article.md 
+    docker run -v $(pwd)/output:/output pyd4vinci/scrapling extract get "https://blog.example.com" /output/article.md 
     ```
 
 - **Extract Specific Content**