Feat/CLET-141 migrate stream docs [MINOR]

[diazproduction]

• Added docs for Stream.

Steps to test

• Go to the website project.
• Run env DOCS_BRANCH=this-pr-branch yarn docs to download the docs files from this PR.
• Run yarn start and go to /docs to check the changes.

[cornelfd]

I think we are missing a few pages (or I'm missing them in the PR): https://transaction-stream.fidel.uk/docs/mobile-sdks-changelog https://transaction-stream.fidel.uk/docs/web-sdk-changelog