Migration finish

[NicolasMassart]

Pull request checklist

Use the following template to make sure your PR fits the ConsenSys documentation standard.

Before creating the PR

Make sure that:

• You've read the contribution guidelines.
• You've previewed your changes locally.

Describe the change

Updated the name of project to EthSigner in some files.

Note: this is the first PR on the migrated doc, so also trying that everything works well.

Issue fixed

• Some remains of copy/paste to update to the right project name
• Version dropdown not activated

Impacted parts

For content changes:

• Documentation content
• Documentation page organization

For tool changes:

• Github Actions workflow
• Build and QA tools (for example, lint or vale)
• MkDocs configuration
• GitHub integration

After creating your PR and tests have finished

Make sure that:

• You've fixed any issues raised by the tests.
• You've previewed your changes (see preview link added in the PR comments)

[rolandtyler]

LGTM