Note backwards compatibility issue on finding root metadata descriptor algorithm

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As raised by @Pfeil in #253 there may be a backward incompatibility from 1.2 if reading 1.0 crates following the algorithm in https://www.researchobject.org/ro-crate/specification/1.2-DRAFT/root-data-entity.html#finding-the-root-data-entity

1.0 crates would have the metadata descriptor as ro-crate-metadata.jsonld https://www.researchobject.org/ro-crate/specification/1.0/index.html#ro-crate-metadata-file-ro-crate-metadatajsonld and so would not match the 1.2 algorithm's search for ro-crate-metadata.json

I am not sure if this would be considered breaking semantic minor version rules https://semver.org/

The opposite -- loading a 1.2 crate with 1.1 algorithm, should however work fine as we have not changed the conformsTo URI prefix

Perhaps the simplest is to suggest loading with 1.1 algorithm if the 1.2 one fails?