fix: add more docs

[travis]

release-please doesn't create a release for chores, so my last attempt to create a new keyring-core release failed.

Add some basic docs, and call this a fix to get release-please to do the right thing.

[codesandbox-ci]

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Sandbox	Source
@w3ui/example-react-file-upload	Configuration
@w3ui/example-react-sign-up-in	Configuration
@w3ui/example-react-uploads-list	Configuration
@w3ui/example-solid-file-upload	Configuration
@w3ui/example-solid-sign-up-in	Configuration
@w3ui/example-solid-uploads-list	Configuration
@w3ui/example-vue-file-upload	Configuration
@w3ui/example-vue-sign-up-in	Configuration
@w3ui/example-vue-uploads-list	Configuration

[travis]

ok one more try at getting release-please to create a release for keyring-core - @yusefnapora I feel like my description of a Space leaves something to be desired, would love your thoughts on the best way to explain spaces to w3ui users and happy to update this ASAP.

for now, self-merging to get the release process going.