docs: remove updates.mdx as we don't maintain it well

I am removing the update.mdx from the repository. This was an attempt
to provide a changelog and news entries so people can keep up to date.
However realistically we don't maintain it well enough. So for now
I am removing it.

Author: dsp-ant

docs/development/updates.mdx

@@ -53,7 +53,6 @@
           {
             "group": "Development",
             "pages": [
-              "development/updates",
               "development/roadmap",
               "development/contributing"
             ]

docs/docs.json

@@ -3,8 +3,6 @@ title: Introduction
 description: 'Get started with the Model Context Protocol (MCP)'
 ---
 
-<Note>C# SDK released! Check out [what else is new.](/development/updates)</Note>
-
 MCP is an open protocol that standardizes how applications provide context to LLMs. Think of MCP like a USB-C port for AI applications. Just as USB-C provides a standardized way to connect your devices to various peripherals and accessories, MCP provides a standardized way to connect AI models to different data sources and tools.
 
 ## Why MCP?