Add examples policy to CONTRIBUTING.md

[jonathanhefner]

New examples/ are costly to review and maintain across SDK changes. Add a policy section stating that example PRs from outside contributors are not accepted, and redirect contributors to open an issue instead.

[pkg-pr-new]

Open in StackBlitz

@modelcontextprotocol/ext-apps

npm i https://pkg.pr.new/@modelcontextprotocol/ext-apps@550

@modelcontextprotocol/server-basic-preact

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-preact@550

@modelcontextprotocol/server-basic-react

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-react@550

@modelcontextprotocol/server-basic-solid

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-solid@550

@modelcontextprotocol/server-basic-svelte

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-svelte@550

@modelcontextprotocol/server-basic-vanillajs

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-vanillajs@550

@modelcontextprotocol/server-basic-vue

npm i https://pkg.pr.new/@modelcontextprotocol/server-basic-vue@550

@modelcontextprotocol/server-budget-allocator

npm i https://pkg.pr.new/@modelcontextprotocol/server-budget-allocator@550

@modelcontextprotocol/server-cohort-heatmap

npm i https://pkg.pr.new/@modelcontextprotocol/server-cohort-heatmap@550

@modelcontextprotocol/server-customer-segmentation

npm i https://pkg.pr.new/@modelcontextprotocol/server-customer-segmentation@550

@modelcontextprotocol/server-debug

npm i https://pkg.pr.new/@modelcontextprotocol/server-debug@550

@modelcontextprotocol/server-map

npm i https://pkg.pr.new/@modelcontextprotocol/server-map@550

@modelcontextprotocol/server-pdf

npm i https://pkg.pr.new/@modelcontextprotocol/server-pdf@550

@modelcontextprotocol/server-scenario-modeler

npm i https://pkg.pr.new/@modelcontextprotocol/server-scenario-modeler@550

@modelcontextprotocol/server-shadertoy

npm i https://pkg.pr.new/@modelcontextprotocol/server-shadertoy@550

@modelcontextprotocol/server-sheet-music

npm i https://pkg.pr.new/@modelcontextprotocol/server-sheet-music@550

@modelcontextprotocol/server-system-monitor

npm i https://pkg.pr.new/@modelcontextprotocol/server-system-monitor@550

@modelcontextprotocol/server-threejs

npm i https://pkg.pr.new/@modelcontextprotocol/server-threejs@550

@modelcontextprotocol/server-transcript

npm i https://pkg.pr.new/@modelcontextprotocol/server-transcript@550

@modelcontextprotocol/server-video-resource

npm i https://pkg.pr.new/@modelcontextprotocol/server-video-resource@550

@modelcontextprotocol/server-wiki-explorer

npm i https://pkg.pr.new/@modelcontextprotocol/server-wiki-explorer@550

commit: f653b3c