Add embedded MkDocs documentation site (#795)

Copy and convert existing MCP documentation into an embedded docs site
using MkDocs with Material theme. Includes client and server guides,
quickstart, development/contributing docs, architecture diagrams, and a
GitHub Actions workflow for publishing to GitHub Pages.

---------

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>

mkdocs.yml

@@ -0,0 +1,88 @@
+site_name: MCP Java SDK
+site_url: https://modelcontextprotocol.github.io/java-sdk/
+site_description: Java SDK for the Model Context Protocol - standardized integration between AI models and tools
+repo_url: https://github.com/modelcontextprotocol/java-sdk
+repo_name: modelcontextprotocol/java-sdk
+edit_uri: edit/main/docs/
+
+theme:
+  name: material
+  favicon: images/favicon.svg
+  logo: images/logo-light.svg
+  palette:
+    - scheme: default
+      primary: green
+      accent: green
+      toggle:
+        icon: material/brightness-7
+        name: Switch to dark mode
+    - scheme: slate
+      primary: green
+      accent: green
+      toggle:
+        icon: material/brightness-4
+        name: Switch to light mode
+  features:
+    - navigation.instant
+    - navigation.instant.progress
+    - navigation.tabs
+    - navigation.tabs.sticky
+    - navigation.sections
+    - navigation.top
+    - navigation.path
+    - navigation.indexes
+    - toc.follow
+    - search.suggest
+    - search.highlight
+    - content.code.copy
+    - content.code.annotate
+    - content.tabs.link
+
+nav:
+  - Getting Started:
+    - Overview: index.md
+    - Quickstart: quickstart.md
+  - MCP Components:
+    - MCP Client: client.md
+    - MCP Server: server.md
+  - Contributing:
+    - Contributing Guide: contributing.md
+    - Documentation: development.md
+  - API Reference: https://javadoc.io/doc/io.modelcontextprotocol.sdk/mcp-core/latest
+
+markdown_extensions:
+  - admonition
+  - pymdownx.details
+  - pymdownx.superfences
+  - pymdownx.tabbed:
+      alternate_style: true
+  - pymdownx.highlight:
+      anchor_linenums: true
+      line_spans: __span
+  - pymdownx.inlinehilite
+  - pymdownx.snippets
+  - pymdownx.mark
+  - pymdownx.critic
+  - pymdownx.caret
+  - pymdownx.keys
+  - pymdownx.tilde
+  - pymdownx.emoji:
+      emoji_index: !!python/name:material.extensions.emoji.twemoji
+      emoji_generator: !!python/name:material.extensions.emoji.to_svg
+  - attr_list
+  - md_in_html
+  - tables
+  - toc:
+      permalink: true
+
+plugins:
+  - search
+
+extra:
+  social:
+    - icon: fontawesome/brands/github
+      link: https://github.com/modelcontextprotocol/java-sdk
+  generator: false
+
+extra_css:
+  - stylesheets/extra.css