Story 2178. Added mentioning of optional computeMetadata and computeMetadataValidation in README.md.
Story 2178. Added mentioning of optional computeMetadata and computeMetadataValidation in README.md.

esdc-esac-esa-int/caom2db,pdowler/caom2db,esdc-esac-esa-int/caom2db,opencadc/caom2db,opencadc/caom2db,pdowler/caom2db