Applicable version of the XSD-schema

1. XSD main version like 2.1 and 2.2, will be updated annually, Q4 is preferred
   Check the XSD update timeline based on known RFCs on https://share.wmda.info/x/GIt0Ew
2. Small changes that have no effect to the structure are possible to be arranged quarterly with version number like 2.2.1, 2.2.2
3. WMDA data upload system will always support 2 XSD versions
4. XSD transition period is one year for organisations.