docs: add docs config and proper example docs overrides

[KevinVandy]

Creates a docs/config.json so that tanstack.com can load docs from this repo.

Also, changed the example's package versions from workspace to their real versions so that they can eventually run in a sandbox on the docs website. (root package.json overrides with workspace* version for local dev still)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 2907083

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[pkg-pr-new]

@tanstack/db-example-react-todo

npm i https://pkg.pr.new/@tanstack/db@115

npm i https://pkg.pr.new/@tanstack/db-collections@115

npm i https://pkg.pr.new/@tanstack/vue-db@115

npm i https://pkg.pr.new/@tanstack/react-db@115

commit: 2907083

[KyleAMathews]

thanks!