chore: oauth2 docs

config.ini.example

...docs/features/security/oauth2/authorization-code-grant.md

docs/pages/docs/features/security/oauth2/configuration.md

docs/pages/docs/features/security/oauth2/enabling-grants.md

docs/pages/docs/features/security/oauth2/installation.md

docs/pages/docs/features/security/oauth2/persistent-data.md

src/Command/StaticPagesBuild.php

src/DatabaseConnectionPoolConfiguration.php

...r/ConfigurationProvider/DatabaseConfigurationProvider.php