Update visual examples and added code examples (#1214)

* update hello react navigation, navigation and params pages

* add examples for headers, params and lifecycle

* add example to lifecycle

* update examples in guides sections

* adjust code formatting in header-buttons.md

* [autofix.ci] apply automated fixes

* update 7.0 version

* [autofix.ci] apply automated fixes

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Co-authored-by: Piotr Fijalkiewicz <piotr.fijalkiewicz@callstack.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Mykola Stanislavchuk <kola.stani@gmail.com>

Author: 4 people