docs(examples): add external auth resource server example (closes #658) - #1967

{ "workflowData": { "owner": "modelcontextprotocol", "repo": "typescript-sdk", "sha": "ddd6cab63b03632393592c260890ab41264b5b74", "ref": "1967" }, "key": "y0TCdVOlZc", "runId": 25189925395, "webhookDebug": { "action": "requested", "head_branch": "feat/external-auth-resource-server-example", "head_repository_full_name": "MukundaKatta/typescript-sdk", "full_name": "modelcontextprotocol/typescript-sdk", "isPullRequest": true, "prNumber": 1967, "prNumberType": "number", "isNewPullRequest": true, "isOldPullRequest": false, "prKey": "MukundaKatta/typescript-sdk:feat/external-auth-resource-server-example", "oldPrDataHash": "uHfQVao29n", "lookupKey": "MukundaKatta/typescript-sdk:feat/external-auth-resource-server-example", "data": { "owner": "modelcontextprotocol", "repo": "typescript-sdk", "sha": "ddd6cab63b03632393592c260890ab41264b5b74", "ref": "1967" } } }