Add fitting LICENSE to repository #8
Description
Would ideally use MIT here, but definitely need to check the ramifications of using parts of Atlassians JSON Schema Viewer (https://github.com/atlassian-labs/json-schema-viewer).
They use Apache License 2.0 themselves: https://github.com/atlassian-labs/json-schema-viewer/blob/master/LICENSE
Think this means we will have to use at least Apache License 2.0 ourselves to be compliant. But I'll need to re-check!
LICENSE has to be added to package.json, too!