Update SDK docs

[alexandratran]

Restructure SDK to have separate how-to page for each platform. This structure has pages with duplicate instructions but more clearly lays out which platforms the SDK supports. Also add a known issue note to the SDK connections page.

preview: https://docs.metamask.io/sdk-restructure/wallet/how-to/use-sdk/

[github-actions[bot]]

Preview published: sdk-restructure

[github-actions[bot]]

Preview published: sdk-restructure

[github-actions[bot]]

Preview published: sdk-restructure

[BelfordZ]

@alexandratran Could you please re-open this PR over on the original docs repo?

https://github.com/MetaMask/metamask-docs

[github-actions[bot]]

Preview published: sdk-restructure