docs: updated readme 'add support keplr wallet'

[liottio]

Description

updated readme added support keplr wallet

Checklist

• Increment the version field in package.json of the package you have made changes in following semantic versioning and using alpha release tagging
• Check the box that allows repo maintainers to update this PR
• Test locally to make sure this feature/fix works
• Run yarn check-all to confirm there are not any associated errors
• Confirm this PR passes Circle CI checks
• Add or update relevant information in the documentation

Docs Checklist

• Include a screenshot of any changes (see docs README on running locally)
• Add/update the appropriate package README (if applicable)
• Add/update the related module in the docs demo (if applicable)
• Add/update the related package in the docs/package.json file (if applicable)