Remove version lineage from Ed-Fi-Core.xsd

Summary of outcomes for Data Standard 2.1

• Problem Addressed: Including the Ed-Fi Version History section in the core schema generates additional steps in the automated build process for the standard.
• High-level Reasoning: There are alternate ways to communicate this information, such as via inclusion in Tech Docs, that would eliminate the need for additional steps.
• Changes Made: Removed Ed-Fi Version History section from the Ed-Fi-Core.xsd file

Original ticket description follows:

This is the section entitled "Ed-Fi Version History"

This info will be moved into TechDocs. The enclosing <documentation> element can be left with the version and date info at top.

The reason for the move is that increasingly we are managing versions in our source code management tools and including this info also generates some unnecessary steps in automated build processes for the standard.