docs: Tag 0.14 version of docs as intermediate solution

docs/getting-started/submission-structure.md

docusaurus.config.js

src/css/custom.css

versioned_docs/version-0.14/account.mdx

versioned_docs/version-0.14/apis/metadata.mdx

versioned_docs/version-0.14/apis/routing-api.mdx

versioned_docs/version-0.14/apis/submission-api.mdx

versioned_docs/version-0.14/changelog.md

...docs/version-0.14/details/authentication/scopes-sender.md

.../version-0.14/details/authentication/scopes-subscriber.md

versioned_docs/version-0.14/details/callbacks.mdx

versioned_docs/version-0.14/details/crypto.md

...oned_docs/version-0.14/details/destination-management.mdx

...d_docs/version-0.14/details/infrastructure-docs/_index.md

...rsion-0.14/details/infrastructure-docs/scopes-internal.md

...d_docs/version-0.14/details/infrastructure-docs/sender.md

...cs/version-0.14/details/infrastructure-docs/subscriber.md

versioned_docs/version-0.14/details/jwk-creation.md

versioned_docs/version-0.14/details/pgp-export.md

versioned_docs/version-0.14/details/schema-reference.md