Replace Navigator references to with existing components
Replace Navigator references to with existing components

Summary:
Navigator page("docs/navigator.html") does not exist anymore b/c the
Navigator component itself has been removed from the package.

Replace Navigator references to other components that are less likely
to be changed over time(e.g. TextInput and Button components).

No plans to test as this change is on README of the repository.

No issue was created b/c this is not a bug on code nor a feature
request. And there already is an awareness of dead Navigation links
floating inside this repository(e.g. #13804).

Thanks for submitting a PR! Please read these instructions carefully:

- [x] Explain the **motivation** for making this change.
- [x] Provide a **test plan** demonstrating that the code is solid.
- [x] Match the **code formatting** of the rest of the codebase.
- [x] Target the `master` branch, NOT a "stable" branch.

[1]: https://medium.com/martinkonicek/what-is-a-test-plan-8bfc840ec171#.y9lcuqqi9
[2]: https://code.facebook.com/cla
[3]: https://travis-ci.org/facebook/react-native
[4]: http://circleci.com/gh/facebook/react-native
[5]: https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md#pull-requests
Closes https://github.com/facebook/react-native/pull/13848

Differential Revision: D5148506

Pulled By: shergin

fbshipit-source-id: e4ecabf05e58efdbe3aca2c4b86e7d884ff6ed62

myntra/react-native,exponent/react-native,Ehesp/react-native,hammerandchisel/react-native,cdlewis/react-native,kesha-antonov/react-native,exponentjs/react-native,forcedotcom/react-native,cdlewis/react-native,PlexChat/react-native,myntra/react-native,exponent/react-native,Guardiannw/react-native,PlexChat/react-native,shrutic123/react-native,skevy/react-native,negativetwelve/react-native,mironiasty/react-native,mironiasty/react-native,cdlewis/react-native,cpunion/react-native,PlexChat/react-native,hoastoolshop/react-native,shrutic123/react-native,Ehesp/react-native,Guardiannw/react-native,hammerandchisel/react-native,jevakallio/react-native,exponentjs/react-native,pandiaraj44/react-native,rickbeerendonk/react-native,gilesvangruisen/react-native,cpunion/react-native,makadaw/react-native,facebook/react-native,mironiasty/react-native,formatlos/react-native,hammerandchisel/react-native,Bhullnatik/react-native,hoangpham95/react-native,forcedotcom/react-native,hoastoolshop/react-native,Ehesp/react-native,doochik/react-native,forcedotcom/react-native,gilesvangruisen/react-native,javache/react-native,frantic/react-native,PlexChat/react-native,doochik/react-native,brentvatne/react-native,hoangpham95/react-native,PlexChat/react-native,frantic/react-native,janicduplessis/react-native,jevakallio/react-native,hoangpham95/react-native,myntra/react-native,forcedotcom/react-native,hoastoolshop/react-native,mironiasty/react-native,facebook/react-native,skevy/react-native,mironiasty/react-native,ptmt/react-native-macos,kesha-antonov/react-native,doochik/react-native,janicduplessis/react-native,Livyli/react-native,hoastoolshop/react-native,pandiaraj44/react-native,kesha-antonov/react-native,forcedotcom/react-native,doochik/react-native,kesha-antonov/react-native,myntra/react-native,PlexChat/react-native,Guardiannw/react-native,rickbeerendonk/react-native,thotegowda/react-native,pandiaraj44/react-native,formatlos/react-native,exponent/react-native,peterp/react-native,gilesvangruisen/react-native,Livyli/react-native,exponent/react-native,tszajna0/react-native,hoangpham95/react-native,negativetwelve/react-native,makadaw/react-native,pandiaraj44/react-native,farazs/react-native,myntra/react-native,javache/react-native,forcedotcom/react-native,cpunion/react-native,rickbeerendonk/react-native,ptmt/react-native-macos,PlexChat/react-native,dikaiosune/react-native,farazs/react-native,gilesvangruisen/react-native,Bhullnatik/react-native,Bhullnatik/react-native,facebook/react-native,skevy/react-native,ptmt/react-native-macos,dikaiosune/react-native,skevy/react-native,Guardiannw/react-native,peterp/react-native,shrutic123/react-native,farazs/react-native,exponentjs/react-native,thotegowda/react-native,Ehesp/react-native,makadaw/react-native,brentvatne/react-native,thotegowda/react-native,peterp/react-native,brentvatne/react-native,hoangpham95/react-native,hoangpham95/react-native,Livyli/react-native,jevakallio/react-native,shrutic123/react-native,shrutic123/react-native,Ehesp/react-native,tszajna0/react-native,exponentjs/react-native,doochik/react-native,janicduplessis/react-native,pandiaraj44/react-native,tszajna0/react-native,tszajna0/react-native,arthuralee/react-native,kesha-antonov/react-native,hoastoolshop/react-native,Bhullnatik/react-native,frantic/react-native,Guardiannw/react-native,hoangpham95/react-native,arthuralee/react-native,doochik/react-native,rickbeerendonk/react-native,ptmt/react-native-macos,jevakallio/react-native,cpunion/react-native,gilesvangruisen/react-native,ptmt/react-native-macos,cdlewis/react-native,cpunion/react-native,makadaw/react-native,formatlos/react-native,formatlos/react-native,shrutic123/react-native,negativetwelve/react-native,dikaiosune/react-native,gilesvangruisen/react-native,shrutic123/react-native,farazs/react-native,dikaiosune/react-native,formatlos/react-native,hoastoolshop/react-native,ptmt/react-native-macos,exponent/react-native,cdlewis/react-native,pandiaraj44/react-native,pandiaraj44/react-native,myntra/react-native,formatlos/react-native,farazs/react-native,brentvatne/react-native,skevy/react-native,Guardiannw/react-native,tszajna0/react-native,makadaw/react-native,exponentjs/react-native,facebook/react-native,hammerandchisel/react-native,Ehesp/react-native,rickbeerendonk/react-native,hoangpham95/react-native,Ehesp/react-native,facebook/react-native,Bhullnatik/react-native,brentvatne/react-native,cdlewis/react-native,exponent/react-native,janicduplessis/react-native,tszajna0/react-native,jevakallio/react-native,skevy/react-native,negativetwelve/react-native,formatlos/react-native,cpunion/react-native,cdlewis/react-native,thotegowda/react-native,javache/react-native,Livyli/react-native,jevakallio/react-native,mironiasty/react-native,javache/react-native,Bhullnatik/react-native,cpunion/react-native,gilesvangruisen/react-native,hoastoolshop/react-native,janicduplessis/react-native,facebook/react-native,thotegowda/react-native,shrutic123/react-native,farazs/react-native,jevakallio/react-nati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