docs(examples): fix codesandbox of optimistic updates typescript example

[zorzysty]

using main property in package.json we can point CodeSandbox to a file we want it to open on load in the embedded version

[codesandbox-ci[bot]]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit df1fc8e19fd1af414c75e316dd74d6e0caa5b658:

Sandbox	Source
@tanstack/query-example-react-basic	Configuration
@tanstack/query-example-react-basic-typescript	Configuration

[codecov-commenter]

Codecov Report

Merging #3950 (df1fc8e) into main (eab6e2c) will increase coverage by 0.41%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3950      +/-   ##
==========================================
+ Coverage   96.36%   96.77%   +0.41%     
==========================================
  Files          45       57      +12     
  Lines        2281     2666     +385     
  Branches      640      782     +142     
==========================================
+ Hits         2198     2580     +382     
- Misses         80       84       +4     
+ Partials        3        2       -1     

Impacted Files	Coverage Δ
src/react/useIsFetching.ts
src/react/useQuery.ts
src/core/infiniteQueryObserver.ts
src/devtools/Explorer.tsx
src/react/tests/utils.tsx
src/react/QueryErrorResetBoundary.tsx
src/core/mutationCache.ts
src/devtools/tests/utils.tsx
src/core/logger.ts
src/devtools/useMediaQuery.ts
... and 92 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 2861b53...df1fc8e. Read the comment docs.