Choose new version number for updated ListedLicense schema

[swinslow]

The schema/ListedLicense.xsd file is now being versioned at schema/schema-version.md.

With #1762 now merged, there are a few further changes we should make:

• need to pick a new version number for the updated schema
• the version number at

  license-list-XML/schema/ListedLicense.xsd

  Line 2 in 2d0af97

  <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:tns="http://www.spdx.org/license" targetNamespace="http://www.spdx.org/license" elementFormDefault="qualified" version="1.0.0">

  should be updated from 1.0.0 to a new number
• the schema-version.md file should be updated accordingly, to note that 1.0.0 was used through version 3.26.0 and the new version for 3.27.0 going forward

@goneall @zvr @xsuchy Would you view the schema changes in #1762 as meaning that the schema version should be bumped to 2.0.0, 1.1.0, or 1.0.1?

[xsuchy]

It is a major change. Let's bump major number. I.e., 2.0.0.