This PR adds the ability to set the port of the React application when
using the generator.
e.g.
```shell
npx nx g @nx/react:app --port 8080
```
This is useful when generating multiple apps and then running them in
parallel.
- Update `/packages/` links to `/nx-api/`
- Convert some unneeded absolute links to relative
- Remove leftover examples doc for the already removed `cypress-project`
generator
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## Current Behavior
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## Expected Behavior
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## Related Issue(s)
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Fixes#26126
