[FX-NULL] Add guide on running visual tests locally

[sashuk]

No Jira ticket.

Description

This pull request adds guide on running visual tests locally (in fact moves it from https://toptal-core.slack.com/archives/GG3F4AS4T/p1712657917104799 to Picasso README file).

How to test

• Check out the https://github.com/toptal/picasso/tree/FX-NULL-update-readme-dsfdksf0?tab=readme-ov-file#running-visual-tests-locally

Development checks

• [N/A] Add changeset according to guidelines (if needed)
• Read CONTRIBUTING.md and Component API principles
• [N/A] Make sure that additions and changes on the design follow Toptal's BASE design, and it's been already discussed with designers at #-base-core
• [N/A] Annotate all props in component with documentation
• [N/A] Create examples for component
• [N/A] Ensure that deployed demo has expected results and good examples
• [N/A] Ensure the changed/created components have not caused accessibility issues. How to use accessibility plugin in storybook.
• Self reviewed
• [N/A] Covered with tests (visual tests included)
• ⚠️ Update pinned message

All development checks should be done and set checked to pass the
GitHub Bot: TODOLess action

PR commands

List of available commands:

• @toptal-bot run package:alpha-release - Release alpha version
• @toptal-anvil ping reviewers - Ping FX team for review

PR Review Guidelines

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   1. Add nit: to your comment. (ex. nit: I'd rename this variable from makeCircle to getCircle)

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[changeset-bot]

⚠️ No Changeset found

Latest commit: d195276

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[sashuk]

@toptal-anvil ping reviewers