Note worthy changes

• Fixed VK (a.k.a VK ID) social account provider. Improved its documentation.
• Added optional support for requesting new email/phone verification codes during signup. See ACCOUNT_EMAIL_VERIFICATION_SUPPORTS_RESEND and ACCOUNT_PHONE_VERIFICATION_SUPPORTS_RESEND.
• Added optional support for changing your email or phone at the verification stage while signing up. See ACCOUNT_EMAIL_VERIFICATION_SUPPORTS_CHANGE and ACCOUNT_PHONE_VERIFICATION_SUPPORTS_CHANGE.
• Added support for Mailcow OAuth2.